This post by DHH discusses issues of scaling and rails through the prism of twitter. In it he offers this solution to the twitter folk.

"Second, when you work with open source and you discover new requirements not met by the software, it's your shining opportunity to give something back. Rather than just sit around idle waiting for some vendor to fix your problems, you get the unique chance of being a steward of your own destiny. To become a participant in the community rather than a mere spectator. This is especially true with frameworks like Rails that are implemented in high-level languages like Ruby. The barriers to contribution are exceptionally low."

This is why I love open source, and I'm sure this sounds odd to many people. Why would I love something that pushes responsibility onto myself? I want to be a steward of my own destiny as DHH eloquently explains. This isn't as clear of a benefit when the problem is a feature that you need but doesn't exist. However, it becomes crystal clear when there is a bug that you need fixed and you don't have to wait around for some vendor to fix it. It's also a clear benefit when you get to add the feature yourself, done the way you want it to meet your needs.

p.s. - soulcast is written in ruby on rails (a framework created by DHH and used by twitter)