From https://code.google.com/p/snes-sdk/: SNES-SDK is a C toolchain and libraries targeting 65816 systems, specifically the Super NES (aka Super Nintendo, Super Famicom). It consists of a version of TCC equipped with a 65816 code generator and modified versions of WLA-DX (assembler and linker) and SNES9x (emulator for running the test suite). It is extremely hacky and very unpolished, but it passes a substantial part of the GCC test suite and even has floating-point support. It also comes with a version of the demo game for the SNES pseudo-C compiler SNESC which has been translated to proper C.
From me: Looks like a pretty good start for coding up homebrew stuff with the peace of mind of NOT coding in assembly. We will see what is the state of this project.
Wiki from original source: https://code.google.com/p/snes-sdk/wiki/C_for_the_65816
Other fork of the original project: https://github.com/optixx/snes-sdk This one lag a bit behind from the latest changes. He is also the dev behind https://www.assembla.com/spaces/quickdev16/wiki.
Other fork of the original project, looks like he is targeting Ubuntu: https://github.com/alesegdia/snes-sdk-linux