All of them, probably. But according to ABC News' Brian Ross (in a report that has been confirmed elsewhere), a "hit list" including "a member of Congress, Pentagon officials, a conservative pundit, executives of an American company," and other targets has been circulating on jihadi web sites.
The FBI recently sent out a bulletin about the list—which features photos of many of the targets and calls for people to post their addresses—and notified the people named. NBC News and ABC News both appear to have the list, but are refusing to release names.
In 2008, Bill O'Reilly claimed loudly (and improbably) that Al Qaeda had him "on a death list." So you can rest assured that if he or any other conservative talker was named in the latest release, we'll be hearing about it soon.
Who do you think it is?