I'm having exactly the same issue, and I can't find anything else onine with information about this problem.
The firewire symbol on the "source" machine freezes, and the Migration Assistant on the "destination" machine just stops at "XXX minutes remaining". I've attempted to complete the migration several times, and the amount of time remaining has varied. I've also upgraded the source machine to 10.4 to see if that would help, and there's no change. I've run Disk Utility on the source machine, and no change.
In my case I have a large iTunes library (>30 gigs), and a large amount of pictures, both in iPhoto, and on the disk drive.
Anyone else having this problem, or have a possible solution?