Are there some resources where one can learn how to develop for Windows Phone using Visual Studio 2010?
Windows Mobile is basically dead - however, if you are referring to Windows Phone (which is replacing Windows Mobile), then yes, you can download, today, Microsoft Visual Studio Express for Windows Phone (CTP).
For resources on learning how to develop, there is a Developer Site for Windows Phone (http://developer.windowsphone.com/).
Yep, in addition to Reed's answers, if you're talking about Windows Phone 7 Series in particular, the info is here (developer.windowsphone.com/windows-phone-7-series).
Also, even if you have Visual Studio 2010 Pro, you'll need to download their whole package, including VS2010 Express to use the new SDK.
Furthermore, unfortunately you can't have any other versions of VS installed on the machine you want to try the SDK on, so you'd be better using a different box, or a virtual machine.
have fun!
Correction
My bad, as Arun Mahapatra points out below, you can run VS2010 express with the phone SDK along with other versions of VS, with only a few caveats.
If you are already familiar with C# development, Charles Petzold will be releasing a free e-book on programming for Windows Phone 7. That should be the main resource you will need, most of it is already available online: http://www.charlespetzold.com/phone/index.html