If you were Microsoft wouldn't you build a library of virus, worms and trojans that could take your rivals(Linux) out?. Wouldn't you develop counter strategies to deal with the plague of Microsoft hole crackers out there? To set-up a counter-strike to tarnish the name of your competition too?
Wouldn't you evaluate all those nice open-source code vulnerabilities and build a virus executable library that could be unleashed sometime in the future (if required)?
Well stay tuned because 2008/2009 are going to be very exciting years.