Eagle Moon is right on the money. I have 3 electrics with maple boards, and 3 with rosewood. They all sound good. Unless you have a strong preference toward one or the other, I'd just go with the one that's:
A) Most aesthetically appealing to you if you're buying from a catalog or online. (or)
B) The one that sounds the best (if you have a bunch to try before buying).
Both Eagle Moon and I have Blizzard Pearl/rosewood '08 Jazzes, and are both very pleased with the tone. (I'm not "authorized" to speak for her, but I've seen her post favorable things about it!

) If I would have had a choice of rosewood or maple when I got mine, I would have probably gone for maple on the Blizzard Pearl, but only because I love the look. Personally, on every other color offered on the Am. Stds., I probably prefer rosewood. So get whichever speaks to you.