darth_hamster called earlier to say our nightly Skype was off because her MacBook Pro was very, very dead after yesterday's software update (stuck on boot). Searching indicates that it's not the iOS 5 update causing problems but rather the 10.7.2 update to OS X Lion
that seems to be a problem. From what I've found online it's only MacBooks that are affected - my iMac upgraded fine - but she's now in the middle of a full backup from Time Machine. (The problem was bad enough it wouldn't even allow a re-install of the OS from the restore disc.)