Toronto general manager JP Riccardi has said that he is willing to listen to offers for Cy Young award winner Roy Halladay. The impetus for such an openness to trading a pitcher like Halladay is due to the Blue Jays struggles this season (a respectable 43-41, but fourth place and seven games back in the AL East) along with the remainder of the $14.25M that Halladay is owed for 2009 and the $15.75M that he is due for 2010. Halladay does have a full no trade clause, but unless he takes a Jake Peavy-like approach, it seems unlikely he'd restrict a trade.
The more interesting question is what it would really take to pry Halladay away from the Blue Jays. Josh Johnson, Ricky Nolasco and Hanley Ramirez from the Marlins? Jon Lester, Clay Buchholz and Jacoby Ellsbury from the Red Sox? In reality, neither team would do a deal such as that, but the example illustrates just how talented Halladay can be. It seems unlikely that the Blue Jays would settle for what the Twins got in return for Johan Santana, the only other pitcher who really fits in Halladay's class in terms of effectiveness and consistency. What would the Blue Jays need to let Halladay go?
The American League seems like an unlikely destination for Halladay. The Blue Jays are probably hesitant to trade him within the AL East (it wouldn't really help that fourth place standing) and no team in the AL Central requires the kind of firepower Halladay brings to win the division. The only reasonable destination in the American League would be Texas. They certainly have the talent within their farm system to get Halladay and a player of his talent level may be the only type of player the Rangers would be willing to part with some of their top prospects.
The NL East is similar to the AL Central in that it's anyone's division to win (save the Nationals). The Phillies would love to add Halladay (or anyone else who can throw above 88), but lack much in their farm system to acquire him. Florida certainly has the talent to interest the Blue Jays as mentioned above, but probably is not interested in adding payroll. The Cardinals seem like a possibility with respect to adding payroll and have some prospects the Blue Jays could be interested in.