patently stupid

Dear Lazyweb,

One of the ways Microsoft threatens the Linux community is by telling customers they’re liable for patent infringement if they run it in their data centers, on workstations, etc. Can someone explain to me how and why customers are liable for patent infringement when another party provided them with the infringing product? It would seem to me that since money changed hands from the customer to the entity selling the product, the liability exists solely with the selling entity. Does this mean if I patent a physical widget and a company infringes on that patent while building a dingus and sells that dingus to a million customers then I can sue those customers for violating my patent? Or is software (or more specifically, open source software through its licenses) somehow special?

Please only email me if you know and cite sources. Do not email me about Microsoft, or whether they have a leg to stand on. Shut up, I don’t care about your opinion.

Update: Adam Williamson is my hero. He says:

http://www.law.cornell.edu/patent/35uscs271.html

U.S. Patent Act

..Part III. Patents and Protection of Patent Rights

….Chapt. 28. Infringement of Patents

“Except as otherwise provided in this title [35 USCS Sects. 1 et seq.],
whoever without authority makes, uses or sells any patented invention,
within the United States during the term of the patent therefor,
infringes the patent.”

Note: “uses” is included in that paragraph.