Eclipse is one of the best desktop based IDE for developing applications. It is used for devloping Java, C++, Python, PHP, Ruby on Rails and various other web technology based applications. IBM has always taken Eclipse platform to a high level by making Eclipse based Lotus Notes Client and Designer platform and other IBM Rational Tools. And so is many third party companies for making their own development tools.
Cloud computing and Platform as a service is emerging a lot these days. To make PaaS powerful like desktop application development we need a perfect web based development platform to develop web application on cloud.
IBM and Eclipse foundation is coming up with a new project called Orion, a web based application development platform which will run on your browser. It would be powered by almost all features of desktop based Eclipse IDE. A prototype of this IDE is available at http://www.eclipse.org/orion/
Project is still in its initial development stage, you can register and try some hands on this IDE.