An application has been filed (local mirror) with the United States Patent and Trademark office by Bitgo Inc. of San Francisco which if accepted would assign patent rights over the process behind Bitcoin multiple signature addresses to BitGo. Titled "Virtual Currency Address Security" the application lists Michael A. Belshe and Joseph William Lee as inventors of the technology. A proof of concept implementation of multi signature addresses was incorporated into the BitcoinJS library in November of 2013.
This is not the first patent to be filed in 2015 by parasites wishing to use outmoded concepts from the fiat world in order to assert control over innovations allowed by Bitcoin. Earlier this year Chin-hao Hu and Pai-tsung Hsu applied for a patent over the process of generating a Bitcoin transaction offline for which they would assign "Intellectual Property" rights to themselves. They titled their patent application Offline Virtual Currency transaction (archive.today local mirror).
Expect the trend of people running to the Patent office and claiming inventorship over phenomena that have long been well documented and applied in practice to Bitcoin throughout at least the remainder of 2015.