Microsoft now has its own security threat and research portal: We launched officially version 1 of the new Malware Protection Center Portal.
 
The portal -- which Microsoft has been testing since April -- contains threat data, security research resources including an encyclopedia of threats, and downloadable signature updates for its antivirus and anti-spyware products. It also lets visitors submit potentially infected files so Microsoft can analyze the samples and provide feedback.

http://www.microsoft.com/security/portal/

And no, we do not sell or buy vulnerabilities! ;-)

Urs