Version 27.9.19 of ArcticFox (which is based on Mozilla Firefox code) is available now. There's a weird bug where you have to mess with your profile data in Application Support but it seems like a solid update. Facebook and YouTube aren't being the machine-bogging monsters they normally are... and time will only tell if that memory leak bug is still there.
So for the time being Snow Leopard users, this is the most up-to-date browser you can use.
https://github.com/wicknix/Arctic-Fox/wiki/Downloads