What Dan said - split DNS is something else (in brief: you create two zones for example.com, one for internally-originated queries and a different yet identically named one for externally-originated queries so that for example an internal user will get 10.0.0.100 for intranet.example.com, but that record won't exist on the external zone or will resolve to a completely different, public IP;
clicky!).
You do probably mean slightly smarter routing, so that you only route internal traffic via the VPN and everything else gets NAT'd or whatever then goes off to t'Internet. Right? Unconfuse us, Ken!!!
EDITED: 24 Jul 2013 19:35 by NUKKLEAR