Last month, we reported (with little surprise) that old iPhone accessories were incompatible with the new iPhone 3G. Apple notes that, while some old iPhone accessories are compatible with the new device, iPhone 3G sports its own Dock, which doesn't even ship inside the box.

Sadly, for those who've upgraded to the new iPhone 3G, the old iPhone's dock is not compatible. However, "two intrepid users have found a simple way to mod their old iPhone docks to work with iPhone 3G," TUAW is reporting. Titled "How to: Modify your 2G dock to fit your 3G iPhone," a small but detailed guide up on LightSourceMedia shows how you can turn the old 2G dock into a suitable docking home for the new 3G handset.

"Annoyingly the 3G iPhone doesn't come with a dock, but no matter, those of us who bought the Apple Bluetooth headset have a dock anyway," Andrew posts. "Except the 3G iPhone doesn't fit a dock that was designed for the 2G iPhone… The 3G iPhone is a little wider and a little thicker in the centre of the back, about 1mm or so. Apple now sells a dock separately for the 3G iPhone, but not a combined iPhone and Bluetooth headset version. The solution is to modify the old headset dock to take the new iPhone. If you previously had a 2G iPhone and want to use the dock from that, the procedure is exactly the same."

Users will need to Place their 3G iPhone in the dock the best way they can. After using a CD pen to mark the bits that need trimming, (for example, the centre 3/4 portion of the back, and the left and right sides), iPhone 3G owners will have to grab a "Dremel type tool" and start removing the excess material, "carefully." Here are the steps pictured below: