yea but its nothing new. there have been lots of software doing things like this for years now. in fact using hamachi for q4 makes the server force 'lan mode' and therefore forces rate settings which are too high for the upload of both the server and client making the game unplayable. my friend hosted once and i tried to connect to him thinking that i coudn't join by ip. q4 was at 999 ping and i couldn't even move. for some reason i tried connecting by typing the ip in game and i was able to play fine.
Tunneling services became popular when the Xbox came out because it tricks the Xbox into thinking the other Xbox is on the same LAN. This allows you to play together using System Link rather than pay for the Xbox Live service. It's pretty cool but it's nowhere near like playing on an actual LAN.
Now there are quite a few programs out there that work for the Xbox, PS2, PSP, and GameCube.