Authentication error fix - I called in VZW Tier 1 support and they couldn't help and I was sent to Tier 2 support. Their fix was to send me an update over the phone and then everything worked after that. I bet they are getting quite a few XV6900 calls and they may start thinking something is wrong with the phones.
GPS works well. With GPSviewer just wait until you get long and lattitude and then minimize don't wait for the whole 3D thing. I had turn by turn directions using Live Search and the whole overlay with Virtual Earth is very slick as it gives you surroundings, buildings, trees, etc. The sat images seem more up to date then Google Maps as it seems they are are missing new bulidings, etc.
Has anyone had issues with custom cubes with the Vista710 ROM? Some don't work at all anymore.