When emerging a bunch of packages, including rails, on a fresh install of 2006.0 (sync on 2006-4-18), emerge bombed on dev-ruby/rubygems. The rubygems ebuild got the following error: ruby: no such file to load -- ubygems (LoadError This was easily fixed by some googling and `RUBYOPT="" emerge rubygems` I don't know what caused it, but I couldn't find a bug about it just for documentation's sake so others might get by with slightly less googling.
Yeah, it's an annoying bug in an older gems version that I've since fixed. It spit out some ewarn information on how to get around it when you emerged the package, but it probably scrolled by during a long emerge.