That's the fear.
It'd be nice if Bush were to channel some Reagan charm and announce her presence at some point, honor her son and then shoot a disarming remark such as "I'm sure Ms. Sheehan would agree about how great America is; where we're free to disagree about war, but we always honor our troops."
On second thought, he should just ignore her and focus on important things :)
Onyx just said she will not be there in order to speak at an anti Bush rally outside, scheduled at the same time.