I want to install this on Ubuntu 10 or 11, any easy way to do that?
(related: I'm amazed that I can't find a third-party ubuntu package for ruby 1.9.2 -- is there one out there?)
You don't specify which version of Ubuntu, which makes any sort of recommendation fairly meaningless (we can't even check that the package dependencies will be satisfied in Ubuntu).
If you're not running a version of Ubuntu that's fairly well in-sync with Debian sid, there's a fairly good chance that the package won't even install -- it'll require newer sonames of libraries than your Ubuntu release has, and that'll preclude the package from ever running successfully. If the package dependencies do match, then it'll install, but might work right. You can try it, but... yeah. I wouldn't trust my production systems to it.
In general, it's not a good idea to try to install Debian packages in Ubuntu, and vice versa -- in cases where the packaging diverges, you're making a lot of work for yourself down the line because you're essentially running a completely untested upgrade path, which is likely to bite you in the butt. In this case, you'll also be bereft of any sort of security updates or general improvements, which running sid packages, you might want.
A general word of caution: never, ever, EVER run any sort of