CentOS 5.3 has been mostly released; mirrors are synced, the .iso images can be downloaded, and I'm currently over 50% done downloading both the 32-bit and 64-bit CentOS DVD image torrents:
32-bit DVD image torrent
64-bit DVD image torrent
(Note that are issues getting these torrent files, but the file is well-seeded, with about 500 seeds and peers for both torrents right now)
I should have both files downloaded this afternoon.
yum update doesn't update to CentOS 5.3 yet, but should by tomorrow this time.