An April Refresh of the Windows Phone 7 programming tools is now available. I've updated all the source code that accompanies the preview edition of my book Programming Windows Phone 7 Series and posted it here.
Most of the changes I had to make are documented in the ReleaseNotes.htm file that accompanies the April Refresh: All XNA programs in this release require setting the size of the back buffer; the WindowsPhone Manifest.xml file (in XNA projects) and the WMAppManifest.xml file (in Silverlight projects) require a list of Capability tags.
In addition, I discovered that the Pressure property of the TouchLocation class in XNA has disappeared. This is very distressing; perhaps if we clap very hard we can get it back.
Both Silverlight and XNA projects continue to have issues with build and deploy configurations if the SUO file is deleted. See the readme.txt file in the root directory of the ZIP containing the new source code.