Mass Effect executive producer Casey Hudson has confirmed via his Twitter feed that your imported character from Mass Effect 2 into Mass Effect 3 will be tweakable:

Casey, mind making that a little more clear? “Tweak” is a little bit vague in my books. Does “tweak” mean that if I feel my Shepard’s nose is a little too big that he can get a nose job? Can my Shepard make the gender transition from male-to-female or vice versa if I so wish? Dammit, 140-character limit for preventing clarity!

Speaking of Casey Hudson, it looks as if he has a message for RipTen’s own Stephanie Gutowski: