After a nigth of troubleshooting 3 different people ruby 1.9.1 problems with gems on debian or ubuntu, looks like theres a project that just might provide some help with that in the future: rvm.
They say that "Easy installation and switching between available Ruby versions and runtimes, without messing up your current Ruby install! rvm also allows you to use multiple versions of ruby in separate terminals concurrently!" - quick, go get a load of this on http://rvm.beginrescueend.com/