Nubs look alike at 9-11 weeks so the private place I went to told me to wait to schedule it as close to 13 weeks as possible because 12 weeks is the "magical week" where genitals start to take form, i.e. girl nubs start to shrink and boy nubs protrude. If you're expecting to see a true hamburger or turtle, you will be disappointed, but yes I believe that they can give you some indication of gender by the angle of the nub. We went ahead and booked a scan for 13 1/2 weeks (going around my DH's schedule) and the tech asked me if I wanted to know. I asked her if it was possible to know so early and she said yes, that she could clearly tell with a 95% accuracy we were having a boy. She said she would be very surprised if it changed and even offered to give us a free scan if she was wrong. We will see what the 20 week scan tells us but I thought it was obvious that the nub was boyish compared to the gender scan I had at 14 weeks with my last DD. By that time though it did look like proper genitals. Amazing how it changes so much from one week to the next.