Yes, NAT-Traversal is supported by VPN Tracker. VPN Tracker supports the current version of NAT-Traversal that uses UDP encapsulated packets on port 4500 (RFC 3947), as well as previous draft versions that send UDP encapsulated packets on port 500. In addition, Cisco's UDP encapsulation is also supported.
NAT-Traversal helps to establish VPNs from networks behind routers that perform Network Address Translation (NAT). Such routers can be found in many places: home DSL routers, wireless hotspots, Internet cafes, hotels, airports, etc. Many mobile ISPs (3G modems) also require NAT-Traversal to be used.
VPN Tracker automatically recognizes if NAT-Traversal is needed, and turns it on and off accordingly. It can even test your local router to see what NAT-Traversal method works best with it.