I just released Flot 0.7! Highlights are multi-axis support, area charts and a pie chart plugin, and a big bunch of bug fixes, including an IE 9 fix and reworked replotting support that reuses the canvas elements to put an end to the memleak troubles. The complete list of changes is here. There are some API changes from the axis rewrite.
In related news, I've moved the source code repository to github to make it easier for other people to contribute.
It has been clear to me for some time that more of the things that are currently inside core Flot needs to move to plugins. As time goes, more specific things turn up on people's wishlist, and right now it's just not possible to satisfy them all without bloating the core. Having specific feature sets in a plugin also makes it much easier for people to customize them a bit by hacking the plugin code without having to maintain a delta with the whole of Flot.
Fortunately, some people have expressed interest in helping out, partly due to me taking a hiatus from the mailing list for some time last year, so with a bit of luck some of these things may happen in a not too distant future. Maybe we'll even get a better hyperlinked format for the documentation, something that has never really managed to climb to the top of my list of priorities so far.