ruby 1.9.1 is mainly stability fixes to ruby 1.9, which had a few .. quirks.
for a less-than-complete guide to ruby 1.9 features, consider reading eigenclass's summary from way back: http://eigenclass.org/hiki.rb?Changes+in+Ruby+1.9
for a less-than-complete guide to ruby 1.9 features, consider reading eigenclass's summary from way back: http://eigenclass.org/hiki.rb?Changes+in+Ruby+1.9
"Last major update on 2007-10-12"
Casual lurking on ruby-core suggests that all sorts of things have changed since then.