I have an iPhone application built as an .ipa file. I also have my device registered on my Apple Developer Connection account. I downloaded the .mobileprovision and dragged both it and the .ipa into iTunes. The app shows up fine in iTunes. When I try to sync, though, I get
The application "FUBAR" was not installed on the iPhone "My Phone" because the application signature is not valid.
What am I missing?
Sounds like it might not work because the two files don't match. You could rebuild the application with the updated .mobileprovision file. Also make sure you don't have two conflicting entries in your keychain. An older one might be confusing things.
James, the mobileprofiles can be overwritten by dragging a new one in - or this thread shows how to remove them: http://discussions.apple.com/thread.jspa?messageID=8315382
make sure you have the right "code signing identity" chosen in XCode... also you need to add an "Entitlements.plist" file to your project, uncheck get-task-allow, and make sure it's referenced by your build settings...
Lots of questions out there about this, see for instance this one: http://stackoverflow.com/questions/1264422/difficulties-with-iphone-ad-hoc-distribution-for-testing