As you can tell from the pictures, the myTouch 4G Slide looks to be a composite of the original myTouch 3G Slide and the myTouch 4G. The front of the myTouch 4G Slide features the same speaker grill, front-facing camera, myTouch logo, and button placement (yes the Genius button is still there) as the myTouch 4G while the slide-out QWERTY keyboard is nearly an exact replica of the original Slide.
I find it exciting that phones are being churned out faster, and with better hardware at a pace the iPhone cannot keep up with. Android will win, will always win. No offence to the Apple fanboys of course.
Timmy
Source: HTC Source