Multi-process is one of the most attractive features of Google Chrome. Multiprocess architecture of Chrome makes it possible to run separate browser windows, tabs, plugins and extensions as separate process. This feature is yet to be integrated within Firefox, and finally Mozilla has started implementing multi-process in Firefox.
Currently this feature is available with the Firefox nightly builds (Minefield). To try it, download latest Firefox nightly, and go to about:config page. Now look for dom.ipc.plugins.enabled, set it to true and restart browser. More details here.
The implementation is in initial phase (and may not work at the moment!), but this is a good news for Firefox users. This will increase stability of Firefox while surfing a ‘heavy’ website or using a ‘buggy’ plugin.