I have been asked a few questions recently regarding developing Windows Phone apps which can access Sharepoint 2010 resources.
The easy answer is… download the following toolkit on CodePlex, the toolkit will help simplify the task of building Windows Phone 7 applications based upon SharePoint 2010 servers running Forms Based Authentication. This toolkit also allows you to use the same libraries to build Silverlight desktop applications.
This first release requires your SharePoint 2010 installation to support Forms Based authentication but once you do that, building applications is fairly trivial.
This toolkit will allow you to do the following:
Once a list item is selected it’s passed to a data-driven page that correctly renders the form based upon the Meta-Data for that List from the server. This includes formatting and validation. The data can even be updated and added back to the server.
You can download the Toolkit from CodePlex at: http://sharepointwp7.codeplex.com