my data migration has stalled do i just quit or what?

I'm having a similar problem. I decided to do the transfer over wifi for a number of reasons (machine location, available cables)... and now both machines have shown an estimated "19 minutes remaining" for about five hours. I have no idea if Migration Assistant is stuck, or if it's just sending a really, really big file.

There doesn't seem to be a way to check status or restart... guessing I just unplug the computer and try again?

Just called Apple support for the same problem. They suggested turning off the machine by holding down power key. When you restart it you'll have the option of running through Setup Assistant/Migration Assistant again. If you were attempting Migration Assistant via wi-fi, they suggest only migrating via ethernet cable or do manual migration of files via external hard drive. They said wi-fi can take days.