Preview at WWDC likely in June, followed by September launch.
Apple Media Event September 7th? iPod Touch, Apple TV, Show Rentals
According to Bloomberg, Apple will use this venue to launch the new iPod Touch, $99 Apple TV, and the 99-cent TV show rental service. The September 7th date also falls on the last day of Apple's back to school promotion where they are offering a free iPod touch with purchase of a Mac.
The new iPod touch screen parts are already being obtained by 3rd party repair shops as shown here:
The screens contain a hole near the top that suggests the iPod touch will be getting a Facetime camera as part of its fall update.