I did this for the first time today with DD(3) and it worked quite well!
I was against it before because I did'nt want DD to see her room as punishment, but rather a place to enjoy being for bedtime and play etc.
However now I have a 10wk old baby as well I can't cope having a crying baby and a stroppy pre-schooler. Just shouting at her gives her negative attention when I have to do something with baby instead of be with her. So I thought by sending her to her room I don't shout and dont give negative attention, and she gets to go away and ponder on her actions (or play with her fairies), and I call her down when I am ready to talk about things and make up.
What do you do?