I have the keyboard dock and I like it. The limitations mentioned above are true and hopefully will be addressed in future OS updates, but I am glad I have it now. It puts the iPad at a nice angle and if you're typing up a document in Pages, it is far, far preferable to using the on screen keyboard. I had to write a 4 page paper for a class and I used the iPad and keyboard dock. Having the arrow keys are great, and being able to hold down shift and arrow to highlight text is really helpful. The only time I touched the screen was to quickly move the curser to someplace that would take too long to arrow to.
Everyone has different needs and the keyboard dock does what I need it to.
To answer the original question, yes, you can plug the USB cable into the back of the keyboard dock and plug it into the wall charger.