From The Providence Journal:

Santana, who has a full-no trade clause and intends to wield it to land a six-year contract extension from any team striking a deal for him, told the Twins that he would veto a trade to any team except the Yankees or Red Sox. He also warned them that he would not accept a deal in-season, forcing the Twins to move him this week or lose him to free agency after the 2008 season, when his current contract expires.

Via Ben.