http://blog.taragana.com/index.php/archive/microsoft-fat-patents-declared-va...
The US Patent and Trademark Office has declared that patents Microsoft holds on file allocation tables (FAT) are valid. Unfortunately Linux OS uses FAT file system.
Public Patent Foundation had moved last year to declare FAT patents invalid , but the US Patent Office ruled that the patent techniques are new and non obvious.
Florian Mueller, a noted campaigner against software patents, said: "This is now a situation in which Microsoft could cause major problems to Linux vendors and users. Microsoft may not want to do that yet… but it gives Microsoft the strategic option to do so at a time of its choosing."
FAT patents now hang as damocles sword on Linux vendors users and may significantly affect its adoption in corporations.