It is absolutely possible, as I was told with DD at 13 weeks. I think the difference can be quite significant between 12 and 13 weeks though, so not sure about about being able to find out at 12w.
I live in Canada (Quebec) where the NT scan is offered to all women. You can choose to do it at the hospital for free, or go to a private clinique where they will also combine the scan with a blood test for increased accuracy in the detection of chromosomal abnormalities, but then you have to pay about 400$. Anyway, if you go to a private clinique, most technicians will give you an 80% guestimate of the gender, while hospital technicians will often tell you that they're job at 12 or 13 weeks is to test for abnormalities, and not to tell you your baby's gender.
Anyhoo short answer is yes, it is possible to find out the gender through ultrasound that early.
And btw, the technician explained to me that the female/male parts are barely visible at 13 weeks, but she can tell by the position of the bones in the pelvic area (or something to that effect anyway). Again, this was in an expensive privite clinic with very high tech equipment.