I installed ruby1.9.1 and rubygems1.9.1 on a Debian squeeze machine today and was surprised by an error on the first try at running gem1.9.1.
/usr/lib/ruby/1.9.1/rubygems/source_index.rb:68:in `installed_spec_directories': undefined method `path' for Gem:Module (NoMethodError)
To workaround this, I added this to /usr/lib/ruby/1.9.1/rubygems.rb:
on line 9.
While that enables me to install gems, it prevents me from using them within Ruby scripts. Ugh.
I ended up finding a machine that thankfully had all the debs from rubygems 1.3.6 which work for me.
If anyone needs these, I can upload them to Amazon S3 or something.