So, this is what you call a "done deal." And not just in the message board sense of the phrase. Looks like Texas A&M will tell the Big XIIish today that it's decided to bolt for the SEC, basically ending the speculative phase of this and calling into question the survival of the Big XIIish.
Texas A&M’s departure from the Big 12 Conference drew closer to reality on Monday when the university’s president, R. Bowen Loftin, sent a letter to the Big 12 board chairman, the Missouri chancellor Brady Deaton, notifying the league that the Aggies would formally withdraw — very likely on Tuesday — according to two college officials with direct knowledge of the decision.
Which is not really a surprise, after the Big XIIish basically told A&M earlier Monday it was free to go. What is new is the very question of the Big XIIish's survival long enough to collect its fee from A&M. Billy Liucci is tweeting that "whispers are getting louder" about the possibility of Oklahoma bolting to the Pac-12; that defection would likely include Oklahoma State and might include another school or two from the Big XIIish. (Everything after the semicolon is my speculation, not Liucci's.)
Liucci, one of those that's been pretty plugged in during this whole saga, thinks that a move might take place next week. I don't think it will take that long. Mike Slive wants this done before kickoff. My guess is that there's a teleconference as soon as Wednesday afternoon, with the decision to accept A&M having already been made. But I can't stress enough that that's just a guess; we're into uncharted waters here, with conference realignment bumping right up next to college football season.
But, as we've said for a couple of weeks now, the only question is the timing. When the season kicks off in 2012, Texas A&M will be a member of the SEC.
UPDATE
Contrary to media reports this morning, Texas A&M did NOT send a withdrawal letter to the Big 12 on Monday. #TAMU #gigem #NYTless than a minute ago via TweetDeck 
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Jason Cook
jason_cook
Jason Cook, the Chief Communications Officer for the Texas A&M University System, has issued this denial of Pete Thamel's report.
UPDATE 2
Thamel is now saying that what happened last night was a phone call between Loftin and Deaton, and no letter has been sent yet. That makes it less formal, apparently.