Mozilla released Firefox 3.6 last week. There are many noticeable improvements compared to Firefox 3.5, but two that stand out to me.
Second, Firefox 3.6's implementation of HTML5 media, or at least audio, is superb. Having spent lots of time hacking on and listening to Zeya on Chrome, Firefox 3.5, and Firefox 3.6, the latter is the one where things most often just seem to work as spec'd. Moreover it's Firefox 3.6 (and only Firefox 3.6) that can consistently maintain the illusion that I'm using a native media player rather than a web-based one. That's colossal.
So, kudos to the Firefox developers.
PSA: the ubuntu-mozilla-daily PPA has nightly builds of Firefox 3.5, 3.6, and 3.7 packaged for all Ubuntu releases since Hardy. It's a low-hassle way to teach an old dog new tricks.