Looks similar to my friends scan picture and she had a boy. I saw the nub on my scan, the way it was pointing indicated a girl and I had a girl. Saying that, it's not always accurate and I think it depends on the stage of your pregnancy.
I wasn't even sure if the nub could be seen in my scan. but I uploaded it to www.ingender.com - as there is a forum for people to guess about your scan and thought it was useful that they also had a big gallery of images and even a couple of quizzes so you can start to see the difference between the 'angle of the dangle' in different scans. Of course it's all just a bit of fun to speculate. Still 1 week to go till my scan and I'm getting more impatient by the second now!