Mine took around an hour too, but the bloody machine kept breaking down because the airconditioning wasnt working in the building, so the equipment was getting too hot. Anyway, we asked for the gender, and the sonographer and baby was in the perfect position to find out, and as soon as he got to the "bits" he said abruptly no I cant tell....I do beleive that some of them just dont want you to know, and it is in their power if they dont want to tell you. A shame really.
So we went and had a 3d scan done at 26 weeks and asked the gender then....She was happy to tell us, as we were paying for the service, as it was a small practice that did DVD's as keepsakes only. However she did get it wrong LOL!
All the best for your scan....I hope you get to find out what it is....Its a little dissapointing when you cant find out on the day......I just hate surprises LOL!