imo, WAIT! I bought the MBP the day they upgraded them in November, and couldn't be happier. I waited 6+ months for it to transition to Merom. Now i'm trying to find a way to sell this thing a week before June so that I can get the latest again!
Possible new features:
LED backlit screen: brighter and longer battery life
Santa Rosa: extremely quick booting times as well as faster application launching, and more battery life.
Small bumb on CPU performance
Possible GPU upgrade
Installed with Leopard already on it.
etc
You'll be happier if you wait. If you buy one now, and they upgrade in June, yours will fall in value by about 300-400. Save the money. It's a hard wait (trust me, i know) but in the end youll have the best MBP money can buy, with the latest OS!