On reading about Google App Inventor for Android - http://appinventor.googlelabs.com/about/ , I thought of searching the web to find out if there are services or IDEs to Code on cloud. Seems like there are - Giving below list of them and also blog post links about these kind of services

http://appinventor.googlelabs.com/about/

http://www.zoho.com/creator/index.html

http://pipes.yahoo.com/pipes/

http://arstechnica.com/open-source/news/2009/02/ide-in-the-cloud-mozilla-labs-browser-based-ide-prototype.ars

http://www.wavemaker.com/

http://kodingen.com/

http://getcodeslam.com/

http://www.sitepoint.com/blogs/2009/02/17/bespin-cloud-coding/

http://web.appstorm.net/roundups/5-great-ides-to-start-coding-in-the-cloud/

http://blog.programmableweb.com/2010/02/17/5-online-ides-that-let-you-code-in-the-cloud/

http://ethercodes.com/