If you signed up for more info, you probably got the same email I did this morning. Now Amazon's Zune HD page will let you pre-order either the 16gb or 32gb Zune HD, and they have the HD docks and other accessories for pre-order as well.
Full specifications can be found at Microsoft's store. If you can resist pre-ordering one, and don't mind buying directly from Microsoft after September 15th, you can get custom engraving on 5 different colors. Anywhere else the choices are black (16gb) and platinum (32gb).