The strangest thing about that 'over capacity' message we get over and over when browsing www.twitter.com is the fact that Twitter chose to replace their core application in a new one developed in Scala. The previous was developed in Ruby. Comparing Twitter availability with Facebook and given the fact that Facebook is more popular and given the fact that Facebook core server side is developed in PHP... it seems there must be something Twitter misses and it probably has nothing with the programming language they chose.