There are now official binaries out for Linux and Mac. They were in private Beta since the April 1, 2012 release, and closed public beta since sometime in October last year.
There are still some minor bugs, and some of these bugs hit some people rather hard, but it runs surprisingly well on Linux considering the port is less than a year old.
I would still consider the Linux version beta quality. However, it does function OK. It functions well enough for me to move my support request vote to another application.
Edit: As of May 2013 the Linux version works perfectly, and it is publicly available. The only reason to continue using Crossover for this is Dogfood Testing. They also ported over some of the improvements from the Linux version over to the Mac version, so from what I've heard people who used to have issues with the Mac version will likely no longer experience those issues.