TO FREE SOFTWARE, THE BIGGEST patent problem (as far as software companies are concerned) is Microsoft, not Apple or IBM (here is a new analysis about Oracle). Microsoft has already grown some patent tentacles, which include patent trolls like Paul Allen and several offshoots created by former Microsoft staff. Two such Microsoft-affiliated software patents proponents put patents in UNIX and Linux. They are called Centrify [1, 2, 3] and Likewise [1, 2, 3, 4], which are merely a nuisance to Samba. It's probably obvious that Samba is strongly against software patents (it was an early adopted of GPLv3), unlike those Microsoft patents boosters who are only good at publicity and faking "open source" (Likewise falsely markets itself as "open source" when it's actually 'open' core, i.e. proprietary).
Aliso Viejo-based Quest Software has sued competitors Centrify Corp. and Likewise Software, Inc., the firm said late Friday, claiming that the two firms infringe on one of its patents, U.S. Patent No. 7,617,501. According to Quest, the patent covers the extension of Windows Group Policy into Unix, Linux, Mac, and other non-Windows computer systems. Quest said it is seeking damages and injunctive relief from Centrify and Likewise.
This is in response to a patent infringement lawsuit that was recently filed by Quest against Centrify and another software company.
Centrify alleges that Quest Authentication Services infringes its US Patent 7,591,005, a key technology of Centrify DirectControl that facilitates the capability for UNIX and Linux service accounts and root accounts to be authenticated within a centralised directory.
--James Plamondon, Microsoft Technical Evangelist. From Exhibit 3096; Comes v. Microsoft litigation [PDF]