Assuming you have Gmail or Dropbox (and you don't already have anti theft software already installed) then you might be able to track your Macbook's IP Address.
If your macbook was stolen, you can use a service like Gmail or Dropbox to find the IP address of your thief. When you log into those services from any computer, it logs the IP address used, and displays your last used IP in your account. In Gmail, it's in the bottom right-hand corner under "Details," and in Dropbox, it's in Settings > Security under the details of each individual computer. If the thief used your computer, the last logged IP address may be theirs instead of yours. Again, though, if they're smart, they didn't use your computer and this trick won't work.
Of course, knowing their IP only gets you so far. You'd still have to file a police report, send a subpoena to that IP addresse's internet provider, and find out where they're located, which could take a long time. Using this method is no guarantee unfortunately Whatever you do, don't try to track the thief down yourself and get your gear back. That could lead to all sorts of trouble.