Mohamed Yamama a Windows Phone Developer Evangelist for Microsoft Middle East & Africa HQ, shared for download a Windows Phone 8 Hands On Labs (Training Kit) on MSDN Blogs
You can now download the Windows Phone 8 Hands On Labs from here.
I am sharing his post here as well. Thank you Mohamed.
And for all WP developers WP8 is here already and this will help you pick up and start developing.