Hey, you didn't say it was going to be Cory Doctorow!
Hard to think of any author more appropriate to spawn this discussion.
Since you had him write your name, it's a lot more personal than somebody else's digital signature, and I think it still would be, even if he had done it with a digitizer. A usb "chop" wouldn't be so cool, though. And the generic "signed copy" with no name is likely to be a casualty in the ebook era, yes. Which is fine by me. It always boggles my mind that people will wait in line to meet an author but then don't want the signature "addressed" to them because it won't increase the "value" of the book as much.