Here. If you haven't seen it yet, or weren't able to get the CDs from the PDC, you'll want to check out the online Longhorn SDK.
Even if you do have the offline LHSDK, you'll want to check out the online version, as it includes experimental support for MSDN Annotations, which lets readers comment on each page.
Here. "If Microsoft succeeds with even a portion of the ambitions expressed, Longhorn will be more secure and reliable by orders of magnitude over all previous versions of Windows."
I sure hope we succeed, then. : )
Here. Before they hit it big on the stage during their keynote demo, Chris Anderson and Don Box recorded their now famous "Lap Around Longhorn" demo for MSDN TV. Enjoy!
Here. The new stuff in Longhorn ain't just for developers. In addition, the Microsoft Windows Hardware Central site has a bunch of resources dedicated to building drivers in Longhorn, including details of the Driver Developer Conference coming up in November.
Here. Sorry for the delay in announcing this, but I had a devil of a time posting blog entries from the PDC. Anyway, the thing I've been working on for the last six months in now live and I've you to take a look and tell me what you think.
If you're a developer interested in knowing about Longhorn so that you can make decisions on your current projects or so you can dive right in and program against the PDC bits, this is the site for you.
The LHDC includes community news on the Editor's Blog (the "Longhorn" category of this blog), tons of articles and whitepapers (with more to come), links to Longhorn samples, directions for MSDN subscribers that want the bits but weren't able to come to the PDC, the Longhorn newsgroups hosted on the web in case you don't like using a newsreader, the Longhorn SDK (with live annotations) and more as I think of it.
Enjoy.