I don't think many Conservatives voted Allen out. I think he lost 90%+ of Independents with 'Macaca', his really weird reaction to the Jewish stuff, his seeming inability to answer direct questions (did you see him on MTP? he was downright embarassing, and that's pretty impressive when you are seated next to Webb), and his attempt to pander to feminist to win that got him killed.
I'm pretty sure most Conservatives did what I would have done: Voted for him, but wondered why the hell he's gone nuts, and praying it's only temporary.
What makes you so sure that Allen was turned out by cut and run conservatives here? There are plenty of Blue Staters moving into Northern Virginia who registered and voted for Webb. Hell, I know some of 'em.
I voted for Allen; I did my part.