According to this new message to the php.internals mailing list (from Lukas Smith) it looks like PHP 5.3 will be rolling out as soon as Thursday!

It looks like nothing critical has popped up since RC4. So it looks like we will be sending the final stable release to the mirrors next Wednesday and announce the release on Thursday barring any critical issues emerging in the next days. In the mean time test test test. If issues are found/fixed please send the patches to internals for review.

Only major issues will be patched over the next few days with the more minor ones waiting for the next release in the series, PHP 5.3.1. Keep an eye here and on the PHP.net site for the official release announcement!