I've been having the "slice" problem with my iPhone too. I have gone through 2 solid 8 hour charging cycles with the AC Adapter and USB cord. The first 8 hour charge cycle was in the dock with wall adapter connected to dock. This never resulted in a full charge. Read the forums last night, tried the reset procedure someone suggested and put on 8 hour charge with USB cord directly in the iPhone (i.e. no dock usage) with the wall adapter. Got up this morning and still had the same problem - never shows a full charge and have no Usage stats whatsoever - just a dash ("-").
I called Apple this morning to report it and the very friendly tech asked if I had tried charging with my Macbook via USB, which I hadn't. She informed me that that would be the only other thing they could suggest to resolve the issue without having to have the iPhone serviced. So I am charging the iPhone on my Macbook as we speak. Also turned off all power management functions on the Macbook so it would not go into sleep mode. The tech said they needed to rule out that I don't have a bad AC Wall Charger or bad USB cable. I am now using my old iPod USB cord to see if it makes a difference.
The Apple tech is supposed to call me back in about 4 and 1/2 hours to see if this fixed it, as she said she has had iPod customers with similar problems in the past and this is how she has resolved it.
Guess I'll wait and see if this fixes it. If not, the Apple tech said I may be able to return the iPhone to the AT&T Store where I purchased it in the morning (if stocks are on hand I suppose).
I'll update here to let everyone know if this fixed the problem.
Macbook Intel Core 2 Duo Mac OS X (10.4.10) 2 GHZ, 2 GB RAM, 120 GB HDD, 15" Powerbook G4, 1GB RAM 1.67 GHZ