I ported Cave Story to SDL, with help from Simon Parzer (who wrote the GP2X specific code and a software sound mixer).
The GP2X version can be downloaded here.
I started work on a GameCube version, but my employer became a registered WiiWare developer and I had to stop.
I got in touch with Pixel, asking him for permission to work on a WiiWare or iPhone version. Unfortunately permission was not granted, indicating that Pixel may have further plans for Cave Story.
