Heroku and Rails 3 - Routing that works locally breaks in cloud

Question

Using Rails 3 Beta 4: I'm getting this error, but can't quite follow why, as it's working locally. It's a pretty small application at the moment, and I can see that one controller is working, but the SessionsController is not. Does this uninitialized constant error look familiar to anyone?

Started GET "/sessions/create?code=2.pzgzK7uPk32dxc9UegmQgA__.3600.1277082000-1799948928%7CnHdN5yk1fcYeG52mHJPdelWVaQY." for 10.248.142.128 at Sun Jun 20 16:08:53 -0700 2010

ActionController::RoutingError (uninitialized constant SessionsController): /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activesupport-3.0.0.beta4/lib/active_support/inflector/methods.rb:103:in constantize' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activesupport-3.0.0.beta4/lib/active_support/inflector/methods.rb:102:in each' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activesupport-3.0.0.beta4/lib/active_support/inflector/methods.rb:102:in constantize' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/routing/route_set.rb:44:in controller' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/routing/route_set.rb:23:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-mount-0.6.4/lib/rack/mount/route_set.rb:148:incall' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-mount-0.6.4/lib/rack/mount/code_generation.rb:89:in recognize' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-mount-0.6.4/lib/rack/mount/code_generation.rb:66:in optimized_each' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-mount-0.6.4/lib/rack/mount/code_generation.rb:88:in recognize' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-mount-0.6.4/lib/rack/mount/route_set.rb:139:incall' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/routing/route_set.rb:457:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/head.rb:14:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/methodoverride.rb:24:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/params_parser.rb:21:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/flash.rb:177:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/session/abstract_store.rb:106:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/cookies.rb:235:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activerecord-3.0.0.beta4/lib/active_record/query_cache.rb:31:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activerecord-3.0.0.beta4/lib/active_record/connection_adapters/abstract/query_cache.rb:28:in cache' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activerecord-3.0.0.beta4/lib/active_record/query_cache.rb:11:in cache' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activerecord-3.0.0.beta4/lib/active_record/query_cache.rb:30:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activerecord-3.0.0.beta4/lib/active_record/connection_adapters/abstract/connection_pool.rb:365:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/callbacks.rb:46:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activesupport-3.0.0.beta4/lib/active_support/callbacks.rb:414:in _run_call_callbacks' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activesupport-3.0.0.beta4/lib/active_support/callbacks.rb:88:in send' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/activesupport-3.0.0.beta4/lib/active_support/callbacks.rb:88:in run_callbacks' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/callbacks.rb:44:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/sendfile.rb:105:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/remote_ip.rb:48:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/show_exceptions.rb:48:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/railties-3.0.0.beta4/lib/rails/rack/logger.rb:14:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/runtime.rb:17:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/lock.rb:11:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/lock.rb:11:in synchronize' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/lock.rb:11:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/actionpack-3.0.0.beta4/lib/action_dispatch/middleware/static.rb:30:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/railties-3.0.0.beta4/lib/rails/application.rb:145:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/railties-3.0.0.beta4/lib/rails/application.rb:81:insend' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/railties-3.0.0.beta4/lib/rails/application.rb:81:in method_missing' /home/heroku_rack/lib/static_assets.rb:9:in call' /home/heroku_rack/lib/last_access.rb:25:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/urlmap.rb:47:in call' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/urlmap.rb:41:in each' /disk1/home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/urlmap.rb:41:in call' /home/heroku_rack/lib/date_header.rb:14:in call' /home/slugs/211466_7d9af6a_ca74/mnt/.bundle/gems/gems/rack-1.1.0/lib/rack/builder.rb:77:in call' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/connection.rb:76:in pre_process' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/connection.rb:74:in catch' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/connection.rb:74:in pre_process' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/connection.rb:57:in process' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/connection.rb:42:in receive_data' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in run_machine' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in run' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/backends/base.rb:57:instart' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/server.rb:156:in start' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/controllers/controller.rb:80:in start' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/runner.rb:177:in send' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/runner.rb:177:in run_command' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/lib/thin/runner.rb:143:in run!' /usr/ruby1.8.7/lib/ruby/gems/1.8/gems/thin-1.2.6/bin/thin:6 /usr/ruby1.8.7/bin/thin:19:inload' /usr/ruby1.8.7/bin/thin:19