In an effort to give the Nintendo 64 emulation scene a "push", one of the Project64 testers has released the source code to v1.6 to the public (unofficially, of course). You can access that here. It's been several years since the PJ64 has seen any activity and perhaps might be dead at this point. PJ64, coded by Zilmar and Jabo, is one of best Nintendo64 emulators. Hopefully this source will help to improve the currently active N64 projects (e.g. Mupen64+ and its various ports)! No word of approval/disapproval from the developers yet. PJ64 is technically at v1.7, however v1.6 includes the biggest improvements from the previous sourcecode release.