With the release of the 4G iPod, Apple stopped including a dock in the package. Not really sure why they did that. A dock costs about $30 to buy seperately.
Instead of spending money on a dock, just make one yourself. Here is a PDF diagram with instructions on building your own Dock using card stock or lightweigh cardboard.
Its also licensed under a Creative Commons license, so if you plan on improving on it, make sure you read the license details.
Nice design, but isn’t it missing the point of the dock–to just drop the damn thing into a container–if you have to manually plug it before setting it on the dock? I think I’ll just stick with my case (vajacases.com) and regular plug. It’s just as pretty.