If you're running Vista and interested in developing for Windows Mobile 6, it's worth the download I'm sure. It'll also work on XP (and heck, Win2000sp4), if you're not bleeding edge. Then again, if you're a WM6 developer, you probably are. :)

Looks like the WM6 SDK and Adaptation Kit are included in this release. One neat feature, the "device" you're emulating can be "cradled" within Windows Vista's Mobile Device Center so you can test syncing. Snazzy.

Yesterday our team released the Device Emulator v2.0.   This version of the Emulator has upgraded performance and some new features

Read: Jason Langridge's WebLog - MR Mobile! : Microsoft device emulator v2.0 released