What other languages? (genuine question)
Twitter from Ruby into Scala and JVM: http://www.artima.com/scalazine/articles/twitter_on_scala.ht...
I think there are two aspects of a language (correct me if I am wrong) -- it's elegance/simplicity/breadth of code produced by programmers that write with it --- and then the efficiency/effectiveness/HW-optimized executable code produced by its compiler once it's run: so how does PHP and Facebook fit in with all this?
The only complex thing about Twitter is its size, and I bet their developers are working round the clock just to keep it from falling apart.
I've worked on many Rails apps, and have upgraded the apps from version to version. It's a pain when key elements of the API shift, but it's not that bad...even when the project has monkey-patched Rails a lot. And twitter certainly has the resources to afford to dedicate a few programmers to this task, so I'm just not sure I buy it.
Supposedly, the problem was caused by Cache Money, but nobody at Twitter wanted to risk moving to a different version again. They're still on 2.0 today. :-)
Another fun fact: Twitter has over 1,500 remote git branches. They also have bright green deer in the reception area of their office. :-)