It's an omen of various sorts when a company that made their name on security and a company that many believe took security as a joke decide to team up. Microsoft and Cisco will soon being working together to create a layer of interoperability between two different standards, namely Microsoft's NAP (Network Access Protection) and Cisco's NAC . The latter, Network Admission Control, is a suite of security protocols implemented by Cisco at various levels to provide things like automated worm control, QoS, et cetera. The basic premise is to allow a next-gen Windows machine to more easily integrate into a secured network:

The goal is to provide single sign-on to a network for machines running Longhorn Server and Windows Vista, and to give third parties building applications with a security component the simplicity of a single programming interface. Interoperability will also mean customers can deploy Cisco's NAC now and upgrade to NAP once Windows Longhorn Server ships, Microsoft said.
While I wouldn't exactly go so far as to say this is a good thing, any collaboration from Microsoft's part to become more active in a security role is a good thing, both for companies and end users.