Tim Greene has a point. 802.11i may or may not be the cure for wireless's ills. Nothing 11i-compliant is out yet. The first certified products will probably be available early next year. Until then, you still want to protect your networks with (OSI model) layer 2 encryption/protection such as AirFortress, Cranite, or 3eTI.
LAYER 3 VPN'S ARE NOT SAFE TO USE IN WIRELESS ENVIRONMENTS!!!