Matt let the WP-Hackers mailing list know that WordPress 2.0 will be released:
Wednesday or Thursday, depending on the phase of the moon.
Now, this means we’ll be rolling K2 over to 2.0-only this week. Feel free to stay with r125, which will be the last version for WordPress 1.5, but know that we won’t be updating it anymore. If you’re interested in being the guy or gal who keeps a 1.5 version up-to-date, then let us know, otherwise it’ll stay the way it is.
Update: Core support people have requested a delay until after Christmas in order to prepare upgrade documentation and enjoy the holidays a bit before the release.
This, combined with the fact I haven’t got the changes to wordpress.org ready, is pretty compelling, so the release is currently planned for the 26th of December.