I don't know why you guyz decided most encryption is done at layer 6?.
Most modern (Checkpoint, Mircosoft, IPsec) VPN's encrypt at layer 3 or 4 (FWZ, IKE, SKIP) which is as low as you can go on a routed/natted network obviosly. as for Wireless Encryption, 802.11b does come with 40 or 128 wep encryption (which would be Layer 2 ).