The second beta of WordPress 2.8 has been released. If you develop plugins or themes, it’s about time to do some testing.
From the looks of things, I project that the final release should be available sometime this June. We may see another beta and a release candidate before then, but it won’t be long now, I don’t think.
As usual, you shouldn’t install it on a production blog. There are bound to be bugs. If you have an extra database handy, feel free to install a test blog and try it out though. This Codex page has an overview of some of the things coming in 2.8.