Patch 2.3.2 has been out on the live realms for a while now, which can only mean that it's time for patch 2.3.3 on the PTRs! Late last night Blizzard launched the 2.3.3 PTRs to little fanfare. No pre-mades are available this time around, so expect to see more testing and less random dueling with epic'd out level 70 characters on the 2.3.3 PTRs. The patch notes are sparse, containing a couple of bugfixes and some improvements to load time, but as with all patches, you never know what unintended (or unmentioned!) changes might have slipped in. MMO Champion has the latest on the patch notes, though their version differs very little from the official version.
Interested in trying the test realm out for yourself? Head over to the official site to download the client and copy one of your existing characters! (Having trouble getting on -- WoWWiki has a great guide to setting up the PTR client.)