The last we heard about the Family Guy MMO, we didn't know what it was. To be perfectly honest, I'm still not 100% sure. It seems like some sort of combination between World of Warcraft and The Simpsons Virtual Springfield. I suppose it won't be a mystery too much longer, with the announcement that Family Guy Online has entered its open beta phase.
Now it's important not to get too excited, although it's a good idea to register as soon as possible. To avoid having too many people in the game at once, the developers are sending out keys in waves based upon when you have registered. If you registered before the keys began to be sent out, there's a chance you are already in the game, possibly even enjoying it (although I hesitate to use the word).
The developers say they're getting through the list as quickly as possible and that access will be granted to your account as soon as they feel your presence (and that of millions of others) won't be enough to crash the servers.