We have recently released the Beta version of the eXo Cloud IDE and would like to get feedback from the Java community. Its a free web-based IDE, with Groovy and JAX-RS support, therefore allowing you to deploy Rest Services directly from the IDE.
Do you see the usage for web-based IDEs? We currently don't see it as a way to replace desktop IDE, but more as the "last mile" for your application. An efficient way to create web applications such as OpenSocial gadgets.
The objective is also to allow direct deployment from the IDE to PaaS offerings such as AppEngine or Amazon Beanstalk.
You can check out the service at http://cloud-ide.com.
Curious to hear feedback.