bossy 4-year-old dd

[megglewell]

Our 4 year old has always been pretty strong-willed but since she started school her bossiness has gone off the scale. She orders us about all the time, pulls her little brother around even when he's protesting, when you tell her not to do something she does it, when you tell her to stop she carries on..it's like she can't help herself. With her friends she's really controlling, dominates all the games, tells them what they want and don't want..
Anyone found any good techniques for dealing with it?