I'm thinking there are some serious issues in the way people are measuring here. It seems like everyone says they can reach a tenth, yet their measurements are up to an inch different. You'd think someone with a hand span of 9.5 inches could reach at least one more white key than someone with 8.5...
As for my hand? I measured very quickly and got roughly 8.25 inches, although when I get home I'll try it again and see if I can find a more accurate measurement. EDIT: I checked, and my hand span is 8 7/8". I can reach a tenth, and can just barely "play" an eleventh (although I could never do it in the context of a piece). I'm 6'1" or 2" though...I've been kinda hoping my hand will continue to grow (I'm only 18) but it hasn't done much of anything in the past couple years, so I've kinda given up hope. Maybe I'll get another growth spurt in my early 20s like my dad (he's 6'3").
Also, a large part of your span (from what my teacher has said) is flexibility, not just hand size. The more you play, the more your hand should stretch out, theoretically, so you might be able to reach a little farther. My teacher's thumb and 5 make a straight line when he reaches as far as he can.