I'm 20 weeks pregnant with our second and we just found out the sex two days ago. We didnt find out with our first baby.
I think if you have no expectations or preferences when you go into your scan, finding out the sex is great as Ive already been able to get rid of baby clothes I don't need and start shopping for gender specific clothes and think more seriously about names. I feel like we're bonding smile
BUT.....if you were like us and went in thinking that you'd like one sex over the other, or even are just expecting one over the other, you may find yourself feeling let down or deflated if it turns out to be the opposite sex. We left feeling a little disappointed (if I'm being honest), but after a day or two to sink in, we're back to excited. smile I think it's okay to feel that briefly, many people won't admit it because it's not politcally correct.
Both ways have their pros and cons but I will say this....if you wait until your baby is born, its REALLY hard to feel any kind of disappointment when you are holding that baby in your arms. If you find out at 20 weeks, you may experience that briefly. But nothing cures it like baby shopping!!! smile