Just spotted this when searching for other answers and thought that it deserved a response, sorry you were ignored for so long. No - Apple wont permit developers to do that as they stupidly maintain the false image that their products can't be infected, which we all know is baloney.
McAfee, and I am sure all the other vendors too, wanted to develop protection for the iPhone/iPad but the idea was rejected by Apple, purely, it would seem, for image sake.
They wont even allow Flash, the lack of which causes all kinds of problems with viewing/navigating web pages in Safari. That at least (IMHO) is a tacit admission by them that there are security issues that they wont talk about because an out-of-date Flash can cause security problems in other browsers.
Family Protection at least is in the iTunes App Store for what it's worth but it's not A/V.
I guess sometime down the road it will take lawsuits when enough people get hit by whatever infection, followed by Government pressure to make them change their minds.