I think I had heard in the past that there was a Unix certification process, but I haven't really looked into it much til this story broke a week or so ago. It's quite interesting. Apparently one of the reasons there are so few certified products is that the certification is costly and it only covers specific kernel revisions (so new ones would not be certified). A lot of what I read explained that this is why no BSD or Linux distros have ever sought certification. I believe it also said that the libraries included in most Linux distros dont implement some of the more obscure functions necessary for certification.