The myTouch Slide is supposed to be a keyboard-packing version of the old HTC Magic. It is rumored to be the replacement for the (possibly) soon-to-be-cancelled Sidekick. The leaked photograph of it (via SlashGear) is fairly unimpressive. It looks like an HTC hero with a sliding QWERTY keyboard. To the Slide's credit, the keyboard looks fantastic. Each of the keys is spaced far enough apart that it should be comfortable to type accurately on.
In terms of specs, the myTouch Slide will sport an ARM11 CPU that is likely to clock in at around 528 MHz. It will have a 320x480 HVGA display, same as the magic, and an optical trackpad instead of a trackball. The Slide will have an SD slot and an LED flash for the camera. It is currently rumored to launch on May 17.