If you can believe the folks at WowInsider.com (formerly WoW.com etc), and the folks at Blizzard themselves, Cataclsym is set to launch on Dec. 7th. Is it coincedence that Blizzard chose to release this on the anniversary of yet another cataclysmic event, the surprise attack on Pearl Harbor? Probably. I'm sure that if that Tuesday happened to be the 5th or 3rd the release would still be the same. Put on your tinfoil hats though, because I'm sure the conspiracy theorists will have some fun with this one.
Personally, I was betting on the 9th or the 16th of November for the release - just enough time for folks to get home from Blizzcon, and far enough in advance that you can have it going full tilt boogie by the Thanksgiving weekend. Holding off until December doesn't surprise me though, since it will instead allow them to roll out 4.0.1 or whatever it is to the live servers around that time, giving them a month of good live testing before the xpac actually goes live.
Since I'm not currently in the Beta, hell my account isn't even active right now, I really can't speak to the changes that we're going to see in the game. Most of what I've read seems promising though, and I'm going to activate my account once the new talents and such go live. I'm going to feel really dumb if it's already live, but I haven't seen the huge explosion indicating that it is yet.
From what I've seen, there is going to be a major shift in the way that we do things. In the end though, our job is still pretty basic. Make the green bars go up, make the red bars go down, and keep the big nasty from eating the squishy folks. The tools we use to do these jobs are changing, but most of us will be right back in the swing of things fairly quickly.
Look for regular posts from now until I retire from Cataclsym. The next few weeks will contain more Starcraft 2 and BC2 than you're probably looking for, as well as some stories about my fiancee's cooking (yes, it's amazing) and a new dishwasher.