Jayway have started a series on porting a Windows Phone app to Windows 8 step by step. Should be an interesting series.

They are covering all of this

1. Introduction
2. Conversion strategy
3. Setting up the project
4. XAML has a new home
5. HttpClient vs. HttpWebRequest
6. Working with third party libraries and JSON
7. Cache and working with storage
8. Navigation
9. Localization of your application
10. Live tiles

Check it out