I presented a session at Devdays on Windows Phone 7 Development. I promised to provide the relevant links to get you started.
Windows Phone Developer Portal
Windows Phone Developer CTP (aka the bits) - You will download a bootstrapper. The bootstrapper will download, and install the relevant bits for you. If you do not have VS2010 RC installed for example, it will install an Express Edition targeted at Windows Phone Development
Silverlight Tools for VS (not 100% if you need this, it might be installed by the Developer CTP)
Expression Blend 4
Blend Phone SDK
Blend for Windows Phone 7 Addin Preview
Application Platform Overview for Windows Phone
Windows Phone UI and Interaction Design
Designing Web Sites for Phone Browsers
Charles Petzold Windows Phone 7 Book (6 chapters) – can download sample code too.
Sample Chapters from Learning Windows Phone Programming
Windows Phone 7 Training Kit
Windows Phone 7 Getting Started Videos
Videos/Slides from MIX – search for “Phone” on the page for relevant sessions.
Windows Phone Forums
I hope this helps.