I'm pretty sure Firefox has run Flash in a separate process for some time now (so when Flash crashes, you get a stripy rectangle saying "oops, a plugin crashed" instead of your entire browser disappearing). I guess the news here is the extra-restrictive sandbox environment.
I think they put development on hold (Nov 4 2011):
"On Nov. 4, 2011, we held a public call to evaluate options for improving Firefox responsiveness including the multi-process Firefox initiative (code name Electrolysis, also known as e10s). The outcome of this discussion was a decision to put the Electrolysis initiative on hold"
I believe they got the plugins seperated out, but put a hold on going further and having individual tabs (or content vs chrome) running in different processes.
Yes. On Linux, where Adobe's Flash was piece of shit (sorry for the language but you can't describe it better), Firefox was using NSPluginWrapper for quite a some time. Similarly, Opera uses its own plugin wrapper. Both of these start Flash (and other plugins) in separate process so when the Flash crashes, it does not take down the browser.
