For the OSX and Windows versions, the SDK package actually includes both development tools (headers, etc) and the runtime; the only reason to offer a package which leaves out the development stuff, is to make the download smaller, which seems unimportant.

You can get a sense of where the Linux support currently stands by looking at share.oculus.com, where third-party developers can submit their games and demos, and you can filter the list by which operating systems they support.