It's funny how things come full circle. Circa 2004, Firefox was the browser that forced Microsoft to reinstate its browser team (which had been disbanded around 2001 after the release of IE6). It had a revolutionary interface, and did a lot of things right (although it did lack some important features that IE6 had). Firefox was pretty much static after that point, adding important features (such as contenteditable), but not pushing the envelope much in terms of interface.

Then Chrome came out. It was rough around the edges, but Google released a new version every few months, and it quickly improved to the point where it was better than everything else. It represented a generational change in user interface paradigms and development cycle time.

So now Firefox has been forced to play catch-up to Chrome, much as IE had to play catch-up to Firefox. To be fair, this happened when Firefox abandoned the monolithic development cycle, but the UI changes represent the full acknowledgement of this.

I wonder where the next revolutionary browser will come from. My intuition is that it will be on the mobile side...