Firefox7 Beta has released by Mozilla just two days after Firefox6s official release. And this Beta release is first in the history of browsers to implement MemShrink.
MemShrink : MemShrink is a project that aims to reduce Firefox's memory consumption nearly 50% of now. Find more about MenShrink
Firefox7 Official version is scheduled to be released on Sept. 27 (wiki.mozilla.com says).
You will be able to download the new Firefox 7 Beta for Windows, Mac and Linux platforms, and as for those who have been running the Firefox beta, they need not worry since their version(s) will be updated automatically. On a slightly different note, Mozilla has also rolled out a beta version of Firefox for Android. It must be noted that Firefox 7′s memory usage will remain constant even if you decide to leave the computer and browser running overnight, where it will free up even more memory whenever you close more tabs.