According to the LA Times and WSJ, Mitt Romney has run the first negative ad of the 2008 Campaign (is this accurate?) — Against Mike Huckabee. Have a look.
I can’t help but add that this approach (for Romney) seems a bit ironic and risky — given the fact that it’s pretty well known that he has (apparently) hired illegal immigrants to take care of his lawn. Seems like Huckabee could create counter-ads that really hit Romney hard on immigration (for hypocrisy) — but does Huckabee have the $$$?