I agree with Kimchi's number, and also about the health risk. And the guy has NEVER played anthing approaching an MLB full-season catching load, so even if he does stay healthy he will almost surely wear down, leading to crappy second half numbers.
Bascially, the Mauer bandwagon is so big that levelheaded managers should just give up owning him unless they already have him as a keeper. I would wager that in almost every league there will be someone who completely overvalues him and takes him way before they should. To me it looks like the Kaz Matsui craze last year, where everyone was projecting ridiculously unrealistic numbers and there was always some yahoo who pounced him way to early. Frankly, if I had him as a keeper, I would consider making a trade. I think right now may be the apex of his value, at least through the 2005 season.