Wired News makes the astute observation that all of the good guys on 24 use Macs and the baddies use PCs. Thus it was easy to spot Jamie as the mole because she was using a Dell. When Wired confronted one of the writers about this, his response was as follows:

“Very clever of you to figure this out,” said writer Michael Loceff in an e-mail. “But your powers of observation could have carried you a little further. For instance, the bad guys use Nokia and the good guys, Ericsson. The good guys play chess and the bad guys play Go. The good guys eat popcorn and reconstituted soy protein and the bad guys eat red meat. The good guys are on the quarter system and the bad guys on semesters. However — both the good guys and the bad guys read Wired (News).”

See, I just knew that Nokia was evil! But semesters…uh oh.
PCs Are Incorrect On TV (Wired News)