There's really no point in stating the obvious, Google has always been a supporter of Mozilla Foundation and especially its Firefox browser.
In case you missed it, there's even an integrated Google search field in the Firefox structure and the homepage is set to Google.com by default. And since this friendship is going so well, it seems that soon Firefox could include features developed by Google and thus promote both brands once more.

Google is already working on building the two brands as a whole and has recently launched an affiliate program for Firefox. And that's not all. Google is also willing to invest in testing several features in Firefox 1.5 Beta 1 like tabbed browsing. As it turns out, users complained about the Back button behavior, because opening a new tab resets the history. Closing of tabs was also a problem for some.

Google also puts some muscle into improving the Firefox browser and since it employs a plenty of Mozilla developers, it has built experimental versions of Firefox, with a different approach on the procedure for browsing with tabs. In spite of these efforts, it is still uncertain if Google's research will find its way into the final Firefox browser.