Here's a handy little reference for those doing Windows programming - the Wiki version of MSDN. At the moment the added content is pretty sparse, but I imagine that the folks at MSDN are hoping for a Wikipedia-like explosion of content...well, the glass could be half full...what's that? A cautious optimist?
Now, I'm not a lawyer, and I fell asleep halfway through reading the license information for the contributed content, but it looks like it's a "post it here and it's free for the world, no guarantees, no patents, no noth'n"...but I could be wrong. Anyone out there an expert at these kinda things?
According to the FAQ, the content you provide is immediate and any reviews are going to be community based, rather than some sort of MS filter, so caveat emptor on the correctness of the content! However, I've personally found that the PInvoke equivalent has been very accurate and helpful - not perfect, but much better than starting from stratch.