I cannot stop marvel at the 'gem' of a useful software that I installed today (www.rubyenterpriseedition.com). As its name was enterprise ruby, earlier my impression was that it was some proprietary software (I had heard websites like twitter using it) but to a pleasant surprise, turned out to be an open source software distributed by Phusion (the same guys behind Passenger deployment tool). It is provided for all *NIX systems and ready to run .deb installer for Ubuntu.
Well, to the point itself, Enterprise Ruby features :
# An enhanced garbage collector. This allows one to reduce memory usage of Ruby on Rails applications (or any Ruby application that takes advantage of the feature) by 33% on average.
# An improved memory allocator. This increases Ruby's performance drastically.
# Various developer tools for debugging memory usage and garbage collector behaviour
A lot of this optimization is POSIX dependent, which is why there is no such version for windows yet. The FAQ page (http://www.rubyenterpriseedition.com/faq.html) demonstrated this and a lot more about the improved platform, which is why a lot of production servers are adopting it.
However, the nicest thing in the whole installation was that you got a lot of commonly used gems installed, which is really appreciative because we otherwise have to manually install or repeatedly try to install via the gem repository (a thing that sadly fails most of the time for me).
Hopefully you find this information helpful. If you feel anything contradictory to that posted above, please do comment as I might be wrong in some areas that I haven't checked out yet.