Brian said he thought print journalists were more likely to be non-biased than broadcasters. While that might have been true in the college ranks, I have always thought the opposite. Print folks can publish just about anything they want. I have never seen a tv newscaster endorse a candidate, but has been common for newspapers for a long time.
Newspapers typically have a slant, either liberal or conservative and that is usually known by it's readers. Since broadcasters are using the public airwaves they are supposed to be non-biased.
The interwebnet however opens up a whole new playing ground. I am guessing the print rules will be followed and should be assumed by readers.
Heres a blog that has more on endorsements:
http://www.poynter.org/column.asp?id=101&aid=135278