So by now you no doubt know that Windows SharePoint Services 3.0 is available for download. But something you might have missed is the fact that we have updated the Windows SharePoint Services 3.0 and Office SharePoint Server 2007 SDKs on MSDN.
You can find the WSS SDK here.
And the MOSS SDK here.
These latest updates represent the "official" (that is, non-Beta) release of both SDKs. We've tried to provide the highest-priority developer information, as completely and accurately as we can. While there are definitely areas of the SDKs we plan on expanding in future updates, if we've done our job then you should have plenty of detailed technical information to get you started developing solutions in the SharePoint environment.
As you go through each SDK, don't be shy about letting us know what works (or doesn't) for you, and what types of information you'd like to see in future updates. I can tell you first hand that the comments you type in on MSDN don't just go into a black hole somewhere; they do indeed make it back to the correct documentation team. And you can always contact me through this blog as well, and I'll try and route your comments to the appropriate person (requests for money or free Zune players will be ignored.)
Just for the sake of completeness, here are the various downloads for WSS: