Why you should switch to 1.9: Three Ruby 1.8 bugs
Ruby 1.8 dies in June 2012. This post shows some small examples, why this is good ;)
Version used for testing: ruby-1.8.7-p352. Everything works well in 1.9.
Bug: Inconsistent Float representation
>> a=1215449.9999999993
=> 1215450.0
>> puts "a as Float: #{a}\na as Integer: #{a.to_i}"
a as Float: 1215450.0
a as Integer: 1215449
Bug: Encoding issues
>> a = "text with ─ unicode"
=> "text with ─ unicode"
>> a.tr "─", '-'
=> "text with --- unicode"
Bug: RUBY_ENGINE
is not defined
Not really a bug, but still pretty annoying. You always have to check if the constants exists before using it.