I received a question at yesterdays ALT-C conference on what articles and resources Microsoft had for cross-platform development, our team (Microsoft Open Technologies) have been working with the open source communities on various projects such as PhoneGap for Windows Phone 7 or jQuery Mobile theme for Windows Phone.

You can find information and resources here http://windowsphone.interoperabilitybridges.com/

You will find pointers to interesting related articles in these posts:

http://blogs.msdn.com/b/obloch/archive/2012/02/24/no-mobility-without-interoperability.aspx

http://blogs.msdn.com/b/obloch/archive/2012/03/05/a-developer-s-perspective-on-the-mobile-ecosystem.aspx

http://blogs.msdn.com/b/obloch/archive/2012/03/08/how-to-approach-mobile-development-today.aspx

http://blogs.msdn.com/b/obloch/archive/2012/03/15/concretely-what-does-interoperability-looks-like-for-mobile-platforms-these-days.aspx

These articles don’t bring a strict recommendation but rather raise the questions a developer should ask himself when considering a cross-platform project.