Firefox announced two weeks of testing for Out of Process Plugins aka OOPP

The next great thing in Firefox is going to be the use of crash-safe plugins aka Out of Process Plugins. They isolate the plugin process from the browser process. The new Firefox with OOPP support is available in the trunk now and in order to test and fix bugs in it, Firefox has announced the beginning of two weeks of testdays. 

In case you didn't understand the purpose of OOPP, when you are using them, the Adobe's Flash or Apple's quicktime plugins will run as a separate computing process from the main browser process. So, if any of these plugins crashes, which is a common cause of most of the firefox trouble , an error will be reported for a specific tab rather than crashing and restarting the whole browser.

The new firefox with OOPP support is available in the trunk now. All you have to do is download and install the test version from the nightly and report in case of crashes, hangs or degraded performance etc. The developers will be available on channel #testday on irc.mozilla.org.

You can find more information here.