If you are thinking about cross device support for Android, IPhone and Windows Phone you will probably have to target the HTML5 wave. Unfortunately as Windows Phone developer you will figure out that putting of your app on device is not very trivial task. This fact will limit you to build apps in HTML5 in offline mode (app which do not need network all the time).
if you are WP developer and wants to build the app once and run it on all devices at the market this is the right project for you. If you are not a WP developer (WP stands for Windows Phone) and wants to run you app at WP, this project will makes you more than happy.
daenet team is proud to announce the first version of the Windows Phone Widget Library (WpWidgetLibrary). This small library provides support for deployment of HTML Application on Windows Phone device . We have been inspired in this project by the great idea of Windows Mobile 6.5 Widget Apps. Now after we have demoed* it live at Mobility Day and after powerful and promising MANGO has been released we are moving step forward and announcing the first version of WpWidgetLibrary (HTML Widgets support for Windows Phone) on CodePlex (http://wpwidgetlibrary.codeplex.com).
Please take also a look on Bahro’s blog.
*We have shown in two sessions at Mobility day in Zagreb how Widgets work on Windows Phone, Windows 8 Metro platform and Android. Sorry for IPhone, but we did two sessions only :)