Well, it's basically certain at this point that World of Warcraft patch 3.3.3 will be live tomorrow after the usual Tuesday server maintenance. I've been covering this topic fairly heavily over the past few weeks, but I'll give you a last minute checklist of big changes you should be aware of:
1. Random Battleground Finder - The new random BG finder tool will now be available, it will put you into a battleground that has enhanced rewards and will also serve as your 'daily battleground quest' the first time it is done on any given day. The system apparently feels and operates very similar to the random dungeon finder, so pretty much everyone should be comfortable with the concept at this point. Battleground marks have been removed with this change, so turn them in at your leisure because they are no longer useful!
2. Balances Changes - Nearly every spec of every class has been modified in some manner. Some of the changes were superfluous or small, including most of the changes made to glyphs. It's worth taking a look at the 3.3.3 PTR Patch Notes
to see exactly how your class has been affected, because it almost certainly has.
3. Dungeon Finder - The random dungeon finder tool has undergone some significant changes; players will no longer have a 15 minute 'kick immunity', so problem players can be removed quickly. The penalty for deserting a random dungeon party has also been increased from 15 minutes to 30 minutes.
4. Crafting Changes - Many recipes have had their requirements reduced, and some transmute style cooldowns have been removed. For example: Titansteel Bars no longer have a cooldown, their price should be expected to drop significantly. The Frozen Orb turn-in vendor in Dalaran will also be available, and will trade you eternal elements, Frost Lotus, Crusader Orbs and Runed Orbs for your Frozen Orbs.
There are also a few minor tweaks to several encounters and a few miscellaneous bug fixes. This isn't a content patch, but it is a fairly large update so you can probably expect extended maintenance to the servers tomorrow.