I was wondering the same thing. Then I found this page http://support.apple.com/kb/HT5570
Says that the trusted device must be something that can receive "Find my iPhone" alerts or SMS. So I think this excludes the Macbooks.
It sure would be nice if you could use your Mac, though. I mean it's your AppleID we're talking about, not your "IOS ID" right? Aren't Macs part of the Apple ecosystem still?