I just got back from 5 days in Vegas for Mix 2010 (where I was a top 5 tweeter). Hopefully by now you've watched the first day's keynote and seen some of the awesomeness unveiled. If not, I'd highly suggest checking it out for demos of Netflix, Four Square, graphic.ly, and other apps running on Windows Phone 7. You'll probably want to check out the sessions on the marketplace, the 'Metro' design, etc. but once you're done you'll probably want to get crackin' writing apps for Windows Phone 7, so I threw together a grab bag of handy links to get you started:

Windows Phone Developer Blog
Windows Phone 7 Series Forum
Community Resources for Windows Phone Development

Videos of MIX10 Windows Phone sessions
Windows Phone 7 Series UI Design & Interaction Guide
Free ebook: Programming Windows Phone 7 Series (DRAFT Preview)
Developing applications and games for Windows Phone 7 Series
Install checklist for Silverlight 4 RC, Blend 4 Beta and Windows Phone Developer tools from MIX10

While not directly related to Windows Phone 7 development, these other recent links can come in real handy when developing for Windows Phone 7 Series:
.toolbox - a cute site teaching basic design concepts
Silverlight Training Course (Silverlight 4)
Visual Studio 2010 XAML Editor IntelliSense Presenter Extension

It should go without saying, but my primary focus going forward right now is Silverlight development on Windows Phone 7 - I am sure I'll be posting quite a bit on it in the coming months.