Matthew Dillon has committed a significant amount of work from Jordan Gordeev’s Summer of Code project, for AMD64 support. (It is very close to being able to completely boot an AMD64 kernel) As he says in the commit message, the code is the product of many folks, but with much credit to Jordan Gordeev for getting the work to this point. As far as I know, Jordan will continue working on this past the Summer of Code, which makes it a double success.