Tracks 2.1.2 is being released today to address the recent security vulnerability in Rails. You can download the release here. All changes can be seen here. Upgrade instructions can be found in the manual.
The next release should be Tracks 2.2, which will contain a lot of improvements. You are welcome to help test Tracks 2.2. In the mean time if you prefer the stable release, 2.1.2 is the best choice.
Please note that Tracks 2.1.x does not support ruby 1.9 and it depends on ruby 1.8.7. Tracks 2.2 will support both ruby 1.8.7 and ruby 1.9. Once 2.2 is released, support for ruby 1.8.7 will be dropped.