When Apple announced the iPhone 4, one of the accessories they announced was the iPhone 4 Dock. I have iPhone 3G/3GS Docks around the house and I figured that the iPhone 4 would require a new dock since the iPhone 4 is a new design from the the 3G/3GS. So without thinking, I went ahead and ordered the new dock. Of course as soon as the order shipped I realized that I would be better off going with the Apple Universal Dock instead. As a matter of fact I already own a couple of the original Universal Docks. The problem with those though is that when you plug in an iPhone you get the "This accessory may not work with your iPhone" message. Of course it does work, it's just that this dock came out before the iPhone and the pin configuration is slightly different. So I just ignore the message and sync/charge. In other parts of the house where I just want charging and I don't want the iPhone to lay down on the surface I had been using the 3G/3GS docks. Of course the NEW Universal Dock is compatible and doesn't have this message.
Although the iPhone 4 Dock is Cheaper, the Apple Universal Dock is a better deal in the long run
The beauty of the Apple Universal Dock is that you buy it once and whenever Apple creates a new iDevice, they also create "universal dock inserts" for that device. The iPhone 4 is no different. They make Universal Dock Inserts for it too. So instead of spending $29 every time the iPhone's (or iPod's) design changes (3 times so far), you can spend $49 once for the Universal Dock + $9 for the new dock inserts (you get 3 in the package for the iPhone 4). They even include them with new iPods. Apple also includes several dock inserts for various iDevices right in the box with the Universal Dock. You also get an Apple Remote so that you can connect the Dock to your stereo speakers or stereo system and then remote control the playback of your audio/video. You spend a little more up front, but you get a better deal in the long run if you plan to upgrade your iDevices on a regular basis.
One more hidden benefit. Apple sells Bumpers for the iPhone 4. With all the reported iPhone 4 reception issues, you may want to seriously consider getting one until they sort this all out. However, like most iPhone cases, you can't dock the iPhone in the iPhone Dock even with Apple's own Bumper installed. However, with the Universal Dock if you REMOVE the iPhone 4 Dock Insert, the iPhone will Dock with the Bumper in place. Perfect. Lastly I should point out that if you do still have your original iPhone 2G dock lying around, rumor has it that the iPhone 4 fits perfectly in it (without the Bumper of course).
I'll be returning my iPhone 4 Docks to the Apple Store and getting Universal Docks instead.
You can get the Apple Universal Dock here for $49.00 (or less).