Looks great, really nice. Minor point, I have a feeling (and can't find evidence to the contrary) that Twitter's stack is actually Java, not Ruby [1]. They may have changed back since then, but I can't find anything about it. Maybe I'm totally off though, and other parts of their stack are rails. I don't know - I'm not really a webdev guy...
[EDIT] - any reason for the downvote? I'm totally fine with being wrong, or have I just completely missed something?
The reason I brought it up was because when you select Ruby, one of the motivational messages opens with, "Twitter uses Ruby to power 400M incredible tweets every day."
http://www.readwriteweb.com/cloud/2011/04/twitter-drops-ruby...