Microsoft proposes a "collective defense" system against computers botnets.

Trying to tackle the ever growing problem of hackers taking over computers and using them to commit all kind of criminal activities as part of rings called botnets, Micrososft has decided to do something about it since PCs are the most susceptible of such crimes. Microsoft's plan calls for blocking computers part of such rings, from accessing the Internet all together.
Experts at the software company call the system "collective defense" modeled after public health measures like vaccinations and quarantines, PC world reports.
Under a new proposal, " PCs would be issued a "health certificate" that showed whether the system was fully patched, that it was running security software and a firewall, and that it was malware-free. Machines with deficiencies would require patching or an antivirus update, while bot-infected PCs might be barred from the Internet. "
The new proposal which could face resistance from privacy advocacy groups, already face criticisms from some Internet experts who foresee the impracticable nature of the proposal.

For more, see pcworld.com