I am currently using Aptana RadRails for Ruby on Rails development on my local system. Now I want to work on a Rails-Application that is hosted on my dedicated server, but unfortunatly RadRails does not provide support for Remote File Access (apart from SVN).
Is there an IDE for Rails-Applications that gives me the ability to work on an application on my remote server transparently?
You're doing it wrong!
Seriously, you should be using source control and you should be releasing your software with a deployment tool like vlad or capistrano.
You run your app locally, commit changes, then run deploys to your server. Once things are setup you shouldn't need to even log in to your server.
Developing the way you're doing is going to cause many headaches and reduce your productivity. Now the snide rails developer comment, if you really cared about productivity you wouldn't be using windows in the first place...
It's not available yet, but Haven will allow you to edit files via FTP/SFTP in your browser. It will also allow you to plug into your source control if that's where your stuff is. It should be a nice alternative to the current fat client options.
Disclaimer: I'm a co-founder of Wikid Labs.