It's definitely fine up until I think your third trimester...at that point, it causes uterine contractions and could cause preterm labor. Even then, I think that would only be if you mbated 100x's a day!)
They say that every orgasm is like a big hug/squeeze of the uterus :) But, I agree I think it is perfectly fine too.
It's absolutely fine. Sex with penetration is fine as well unless your Dr. has advised you against it for some reason. There is no medical reason to abstain from sexual activity during pregnancy. Enjoy!