In theory, the hardware supports this.
In practice, it would require software support. Current Macintosh computers with firewire can mount another computer's storage as a drive volume on boot. I suspect this will be the route Apple takes if they include this feature, rather than using it to create an ad-hoc TCP/IP network.
A Macworld article by Dan Frakes and Dan Moren states:
On the new MacBook Pro models, you can use Target Disk Mode over a computer-to-computer Thunderbolt connection. (We assume this will be the case with future Thunderbolt-equipped Macs, as well.) However, Mac OS X’s Migration Assistant software doesn’t currently support Thunderbolt connections.