Public Patent Foundation: Linux potentially infringes 283 patents
Linux potentially infringes 283 patents, including 27 held by Microsoft but none that have been validated by court judgments, according to a group that sells insurance to protect those using or selling Linux against intellectual-property litigation.
CNet is covering news regarding research done for Open Source Risk Management , a company that sells legal protection against Linux copyright-infringement benefits.
Rachiver of the Free Software Foundation opinion however is that of patents challenged in court, about half are found to be invalid and that the number for a package like Linux isn't unusually high.
Source: C|Net News