A photo (see below) of the drum kit for Guitar Hero 4 leaked onto the internet today. In a photo scanned from Game Informer magazine, its evident that the drums will have three main drum pads, two cymbals and a foot pedal. Unfortunately, this likely will make the Rock Band drum kit incompatible with GH4 since that has four drum pads and a foot pedal.
Other details that were revealed in Game Informer include the addition of a Guitar Hero Tunes service that will enable gamers to create and share their own songs. Also, songs by Van Halen, Sublime, Linkin Park and the Eagles have been confirmed.

Retro tack.
Why don't we go back to the 80s and get out our Yamaha electronic drum kits?