Yesterday Mozilla released a new Firefox 3.6 point release including regular stability fixes and a plugin crash protection system that was originally planned for Firefox 3.7.
The crash protection isolates plugins in their own process, meaning that a plugin will not bring down the entire browser when it crashes or freezes. Mozilla states that one of three browser crashes are caused by third-party plugins.
Currently only Linux and Windows include the crash protection, Mac users will have to wait for Firefox 4 planned to be released later this year. This is a fantastic addition in a point release!