Slim2:~ phrogz$ ruby -v && gem -v
ruby 1.9.1p0 (2009-01-30 revision 21907) [i386-darwin9.6.0]
1.3.1

Slim2:~ phrogz$ sudo gem install fastri
A small note about RubyGems + FastRI
====================================
<snip>
Successfully installed fastri-0.3.1.1
1 gem installed
Installing ri documentation for fastri-0.3.1.1...
Updating class cache with 1691 classes...
Installing RDoc documentation for fastri-0.3.1.1...

Slim2:~ phrogz$ qri
/usr/local/lib/ruby/gems/1.9.1/gems/fastri-0.3.1.1/lib/fastri/util.rb:38:in `require': no such file to load --
rdoc/ri/ri_paths (LoadError)
	from /usr/local/lib/ruby/gems/1.9.1/gems/fastri-0.3.1.1/lib/fastri/util.rb:38:in `<top (required)>'
	from /usr/local/lib/ruby/gems/1.9.1/gems/fastri-0.3.1.1/bin/qri:6:in `require'
	from /usr/local/lib/ruby/gems/1.9.1/gems/fastri-0.3.1.1/bin/qri:6:in `<top (required)>'
	from /usr/local/bin/qri:19:in `load'
	from /usr/local/bin/qri:19:in `<main>'