Here is some info, what its worth, I dunno....
I just got an HTC Imagio on Alltel Plan, now owned by Verizon, when I activated it, I was pushed the Alltel PRL. Alltel does not have a carrier name listed, like on the today screen of manila, or the dialer, its just blank. See here...
I noticed when using the phone like this, with no carrier name, Bing had the locate me option on the main screen, however no matter what you did, it would never work. I also could not get the My Location feature to work on the weather tab of Manila. After changing to a Verizon PRL, Location is now working in Manila and Google Maps, but the option is now gone from the main screen of Bing, and is greyed out in the settings. I think that the Bing app just reads the carrier name, and assumes since its CDMA and cannot use CellID, the feature wont work and disables it.
Hope this helps a bit.