This (home grown) blog is now running on Ruby 1.9. Since I wrote it using Sinatra and couch-rest, it was pretty easy to get working. The only real trick was adding a fake JSON gem to fulfill a dependency on JSON (which is now part of Ruby 1.9). I found this reference on the IsItRuby19 which came in very handy in determining which gems work on Ruby 1.9.
Site Running Ruby 1.9