I'm using ruby 1.8.6 p111. But some people seem to think that version 1.8.5 is better. Should I give it a whirl?
I think that the better choice is always the latest version of each language, framework an so on, because software is error-prone and new releases can solve many bugs 
Cheers,
Paulo Cassiano.
Unless there's been a fix, Rails > 1.2.3 threw exceptions on Ruby 1.8.5
In theory, using 1.8.6 is best. More importantly: in practice (I build and maintain rails/ruby apps full-time) I have had no issues with rails 2.0.* and ruby 1.8.6p-*