Scammers have been around for a while now pushing rogue security software through email messages and fake websites, but as Kirsten Kliphouse pointed out last May they've also starting calling users on the phone and posing as technical support for a reputable company (such as Microsoft) in order to try to defraud users out of money or for other nefarious purposes. And as with any good con artist they often know something about the person they are calling, and their pitch can sound very convincing and scary. So please remember to be careful and skeptical.
If you have had a suspicious or phony support experience, Microsoft would like to hear about it so we can work with law enforcement to put a stop to these scams and bring the perpetrators to justice. Another team in my group has released a web form that you can use to report a tech support scam to Microsoft to help us catch these cybercriminals. The form is here:
Report a technical support scam to Microsoft
You can submit the report anonymously or provide contact information (in Question 10) if we can contact you if we have questions. Either way, it's a great way to go on the offensive.
For more information about how Microsoft is taking action against these scammers, see this blog post by Courtney Gregoire (Senior Attorney, Microsoft Digital Crimes Unit) about a civil lawsuit Microsoft recently filed in federal court in the Central District of California against Omnitech Support and related entities for unfair and deceptive business practices and trademark infringement.