Of course, the real underlying question here is, would Corbis be going after us for posting pictures of Kerry if we were supporting his candidacy?
That is a fair question, but -- in terms of the legal situation -- irrelevant to the matter at hand.
Linking to a copyrighted image is not copyright infringement. Hosting a copy of a copyrighted image that is not utilized under the Fair Use exemption of 17 United States Code 107 is. Thus, even in such a case, it is not Free Republic that is violating copyright; it is the site that hosts said image.
I believe Corbis is using the threat of legal action when they know full well they have no leg on which to stand in any court of law.
No.