Linux Mint 9 'Isadora' is almost out of beta and should be moving into Release Candidate soon. This is FAST, considering that Ubuntu 10.04 'Lucid Lynx' was only released yesterday :3 So, Linux Mint 9 should be released as stable fairly soon, probably in the next few weeks.
This will be a Long-Term Support (LTS) release, meaning that it will receive regular security, patch and performance updates for the next two - three years. If you were considering trying Linux Mint, this would be a good release to jump in on.