I've had problems with multiple ruby versions installed, couldn't install animation gem properly. The latest Compass has it included so it might solve it for me. I don't need ruby for anything else so ruby version isn't important for me.
$ gem list
*** LOCAL GEMS ***
animation (0.1.alpha.3)
chunky_png (1.2.8)
compass (0.12.2)
compass-core (1.0.3)
compass-import-once (1.0.5)
ffi (1.9.3)
fssm (0.2.10)
i18n (0.7.0)
multi_json (1.11.2)
oily_png (1.1.0)
rb-fsevent (0.9.5)
rb-inotify (0.9.2)
rdoc (3.9.4)
sass (3.4.18, 3.2.12)
$ sass -v
Sass 3.4.18 (Selective Steve)
$ compass -v
Errno::ENOENT on line ["25"] of /usr/lib/ruby/vendor_ruby/compass/version.rb: No such file or directory - /usr/lib/ruby/vendor_ruby/compass/../../VERSION.yml
Run with --trace to see the full backtrace