I have been enticed to install Gears by the offline support in Gmail, Google Reader and Wordpress, but was unable to easily find a current build to install. To save people trawling through the net, I have listed the builds available here.
The files are linked as XPI files, so a simple click on the links below should bring up the install dialogue. I will update this post as new versions come out.
gears-linux-x86_64-opt-05210.xpi (Current as of 18/05/09)