Now this is interesting.

Heroku lets you build and deploy Ruby on Rails applications entirely through a web browser, no local installation needed at all.

I haven't tried this yet, but there are a few things I really love about this concept, and that's the potential leverage it offers.

• Your application is already deployed as soon as you create it, thus soothing Rails deployment pains.
• You can tap into Amazon Elastic Compute Cloud to scale out certain parts of you system, again improving the deployment scenario.
• You can share your projects with others, and collaborate to improve them. This could mean having your software matured and improved through mutually beneficial development.

I personally think it will be quite some time before the online IDE experience is as good as a local installed IDE, but the other benefits seem compelling. But, I like the idea of an IDE that lives in the browser.

You really should really go and check out the features.

Note, I originallly learnt about this at the 37Signals Blog