We have (with DD 3) and have had (with DD8) the same issue too. I noticed it was especially difficult if the other 3 year olds ( 2 or 1) were not as verbal as my DDs were. Both of mine were talkers from early on and my first one was a motor mouth of unbelievable proportions at age 1! For them if a child can't actually keep up with them verbally they are not interested in trying to play with them. They have both actually told us that this is the problem at various stages too.
DD8 still has some issues playing with other 8 yr olds if they can't understand what she is talking about. She is getting better about using easier words to explain things, but more often than not she simply becomes bossy or annoyed and walks away in disgust.
I can't even begin to count the number of times I've had to play in her imaginary games at a park full of kids because they can't verbally communicate at their level with the kids around them. Sometimes this has lead to older kids coming over and joining in or parents asking why we're so protective of them that we won't let them play with other kids, but that's life.
