According to Craig Calcaterra of NBC Sports the Cardinals are in on the Roy Oswalt sweepstakes:
In fact, the Astros have been talking with Cardinals GM John Mozeliak for several days now, and Oswalt is quite amenable to go to St. Louis if the teams can agree on what players will head back to Houston. For their part, the Cardinals are convinced that matching Roy Oswalt up with Dave Duncan would take a guy who is already an ace and turn him back into the Cy Young candidate he was a few years ago. I'll stop believing stuff like that when Dave Duncan actually fails for once. Which I wouldn't bet on, frankly.
Of course, the big issue everyone has been talking about today has been Oswalt's desire that his 2012 option be picked up. That's $16 million, and that ain't hay. My source tells me, however, that Oswalt would be willing to work with the Cardinals to make the option more palatable, possibly in terms of deferring some money. The sides aren't quite that far yet.
Oswalt is owed $16 million in 2011 and has a $16 million club option in 2012; a tentative deal with the Philadelphia Phillies fell through because he demanded they pick up the option before he'd waive the no-trade clause.