So could I use my little point and shoot digital camera in *just* the lobby and never take it out in the actual concert area?
As stated, digital cameras are not allowed, with exceptions for sponsors, press, band members and the like. If your phone can pictures or do video, that's ok, you can bring it in to the show, just don't use it for pictures or video of the bands - you can use it in the lobby though.
Why the arbitrary distinction with phones? Because it's not reasonable to prevent people from bringing their phones with them, and they have legitimate uses.
Hope that helps a bit...
Thanks,
Chris