Not Open Source, but the next best thing?

I'm not really interested in a big arguement on the merits of Open Source software, I think it has its place in the software world, and so does closed source. So whats the next best thing? Open and well documented API's, SDK's, and protocols. - Outline the MSN assistant with the MSN API, and Speech SDK. Make note of the MSN protocol. - Why this is great, overwrite, or side by side