My cousin and his wife had a sex reveal party and I thought it was awesome.
They made it very clear on the invitation that they did NOT want anyone to bring gifts, as they were going to have an actual shower later on.
The had also just moved into their first house, so they kind of double it as a house warming party, but still insisted on no gifts for that either.
The baby is the first grandchild on his wife's side of the family, so the whole entire pregnancy has been a big deal to them.
It was an awesome party, outdoors, lots of food. Everyone was asked to wear pink or blue to 'vote' for what you think. Then they revealed by passing out cupcakes to everyone to bite into at the same time, and in the middle was blue icing!