Hannity's Giuiliani fundraiser isn't the first. He also did so for Rick Santorum.
Aside from the contrast with the degree to which nonexistent blogger ethics issues are highlighted, I really don't think this is a problem as long as it's disclosed with some regularity. If Hannity wants to present himself as a "Giuliani supporter" on his show that's fine with me. It's better that he presents himself as such instead of pretending he doesn't have a favored candidate when he actually does.
