What IP Address does your friend have recorded, the one allocated by his ISP? If so, it might be worth contacting his ISP and notifying them that the laptop has been stolen and hopefully the ISP can assist when/if the laptop connects to the ISP. Depending on the thief, the thief might not even connect the laptop to the same ISP or connect to the internet at all. The thief could also decide that once all the interesting data on the laptop has been extracted to then format the laptop. 

In order to track the laptop's location, the laptop will have to have had some tracking software installed prior to being stolen. Something like the following, (both free) can help: http://preyproject.com/ or http://adeona.cs.washington.edu/

The IP address will change depending on where it connects to, and the serial number may or may not get sent during updates (depending on the configuration) and would require a court order to force the issue.

There is software that can be uses to "phone home" when stolen, but like was said, can be deleted easily enough. Unless you took precautions in advance against such an incident, the laptop is good as gone. Sorry.