Notes for my own future reference:
After upgrading to 10.6.x (and running all available software updates), if someone cannot connect to a previously-available SaMBa share over the network:
killall -9 NetAuthAgent
… and try again. Worked for Nate’s machine.
Note also that Migration Assistant worked over the network for the very first time today. I had 2 MacBooks (1 aluminum with no Firewire, and 1 new Pro unibody) hanging off an isolated gigabit switch. The new one complained about lost network connectivity once; I suggest disabling screensaver & sleeping before doing this again in the future.
Everything seems fine until/unless I hear otherwise.
Added 2/8/10: Dunno if it’s related to Snow Leopard (what OS X version is Jim running?), but a failed firmware update could very well fuck up an otherwise problem-free MacBook Pro. Apple has a Firmware Restoration process involving burning a CD.