I am curious about this issue also. I've created "My Places" with Bing Maps in my PC but would like to be able to view those places with the Bing Maps App on my WP8 / HTC 8x. It seems like this integration should be automatic but I'm not seeing it. Is this possible with WP 8?
I too am wondering about this. Coming from Android the lack of polish on Bing Maps vs Google Maps is stark. This is just one tiny area where the integration seems obvious. Come on Bing-WinPhone teams, make it work!