Good thing for me I'll be able to play skyrim on my laptop while my desktop is updating : ) and vice versa.
I'm not sure that you can be logged in on the same account, simultaneously, on two computers. I think Steam prevents that (I've never tried it, but that's how I understand it works). You could play another Steam game you might have on the same account on the same computer while steam is updating in the background. However, truth be told, most gamesas patches, historically at least, haven't been very large (DLC might be large, but usually "patches" are relatively small and download in a few minutes on a broadband connection), so I wouldn't worry about it too much.