I doubt the Yanks will give up on Igawa this quickly , but I can't see the team going back to Pavano if Hughes shows any signs of being effective, which I think he will.  

If the Yankees were planning on giving Hughes only a few starts, I think they would've said so before hand.  They're a very media-savvy organization, and will not it to look like Hughes has "failed" in the eyes of the media if he gets sent back down.  Since they have not said anything about their plans, I have to assume that Hughes is going to get every chance to stick.

Deciding when to use your waiver claim is always an important decision in fantasy leagues, but I don't see how you could go wrong picking Hughes.  He's the best pitcher in the minor leagues, and he's getting a great chance to pitch for one of the best offenses in baseball.  No prospects come with 100% certainty, so you can't fault Hughes for being a slight risk.  I wouldn't hesitate to get him if I had the chance.

but I'm not sure the he will be that great in his first season. I think he'll be a great fantasy option in '08.

He'll stick.  I don't know that he's ready, but the Yanks will give him every opportunity.  The WANT him to stick, and unless he's getting completely shelled I can't imagine they'll send him back anytime soon.  Georgie wants to see him with the big club, and the fans think he's the next Roger Clemens.