Dalton Del Don and I talked about this on the radio today and both agreed the Cardinals (if and when they decide they're really out of contention) should waive Pujols.
Pujols' next six weeks plus playoff contributions is a massive asset at his current price that will be wasted if he remains on a non-contending team. The Cardinals could waive him, and then when he's claimed, they'd have two days to work out a deal with the claiming team or rescind the waiver.
Pujols (as a 5 and 10 guy) would have to agree to any trade, but why wouldn't he at least consider one that landed him in the playoffs and gave him a real preview of one of his possible 2012 destinations? Would he not want to consider finishing out his career in Texas where he'd have a far greater chance of destroying all the all-time HR, RBI and runs records?
From the Cardinals perspective, they could get a great haul of prospects and avoid having to try and re-sign Pujols at $30 million a year for 10 years in his 30s. As it is, they'll get draft picks if he walks, but why not see if SFO or TEX were willing to offer far more than the value of the draft picks?
The only downside I could see is that Pujols is upset by the move and refuses to re-sign. But he might not re-sign anyway, and it's not even clear that it's in the team's interest to re-sign him, given the cost. If it were, the team would have given him an extension before the season.