Codebender, a cloud-based IDE for Arduino is coming soon. If you like the look of it, you can back it on Indigogo (28 days left).  I backed it at the $150 level, which gets you and Ethernet Arduino, with a special bootloader that lets you program and download code from the Web. 

From the site's description:

Time to revolutionize the way you develop and hack on your projects. codebender is a platform that helps your next idea come to life. Wether you are a maker, a hardware hacker or an artist, codebender allows you to code on the web, faster and easier, using our awesome web editor. Host your Arduino sketches on the cloud and use our next-gen compiler to build and debug your sketches from your browser. When you are done, upload them to your Arduino, straight from your browser. No installations required. Coming soon.