A few weeks ago I blogged about What's New in Windows Mobile 6 for Developers, you can also check the MSDN article on the same topic. The Windows Mobile 6 SDK is now available for download. You can get it here. It includes new emulators for Standard and Professional editions.
On May 1st there will be an update to the SDK with improved documentation, emulators, code samples and more. For more information on what is included in the SDK check Fernando's blog
I am sure you are dying to get your hands on a Windows Mobile 6 phone. The only one that is available now is the T-mobile Dash, as T-Mobile has announced a free upgrade will be available in the future. While you can get it with WM5.0, we know the upgrade is coming soon. Plus you can still get it at a special discount for MSDN developers here