I threw out my bedside clock long ago in favor of my iPhone.
The dock is a perfect stand to make the phone readily accessible and easy to use with one hand when checking the time or hitting snooze.
If you are like me you probably have about 3 redundant docks laying around the house that came with various purchases.
On top of those I had one dual dock that came with my bluetooth headset. The dual dock was perfect, it charged both my phone and my headset, kept them conveniently locater near one another, and made for one less cord to clutter and gather dust.
One problem, the old iPhone dock is not compatible with the 3g....worse there doesn't seem to be a dual dock available for purchase.
It was time to do some modification.
Before going out into the garage to perform surgery I found this article:
Lightsource Media
A few things to mention:
A dremel will really make this easier. A tapered bit, and a small round diamond bit really work well together
Use a carpenters pencil or a regular pencil to trace your outline.
Use tape to cover the holes and to protect the metal plug. I used electrical tape, it is more resilient.
Go slowly on high speed. Do a little then test the fit. The back curve needs the most. The sides get fitted pretty quickly. The phone tapers towards the bottom so grind accordingly.
Use compressed air to clean everything.
Finish it with 180 grit, then 600 wet sand.
If you do it right it will be plenty smooth and even take on a shine.
The dock works just fine and will do until the real deal hits the shelves.