Since SCO filed its lawsuit against IBM several years ago, a number of vendors have stepped forward to indemnify their customers from suit if the customer becomes embroiled in any litigation involving open source software that the vendor distributed.
Novell, who had already provided protection to its customers, took indemnification to the next level recently with its deal with Microsoft. The Microsoft-Novell partnership has both vendors paying for patent licenses and agreeing not to sue one another's customers. Everyone, conventional wisdom is saying, is fair game (see My Enemy, My Partner: The Microsoft-Novell Alliance).
http://www.linux-mag.com/content/view/2646/