UPDATE: Now, it seems that HP is not going to release the Slate as a consumer product but "for the enterprise." Engadget reported that while speaking at the Fortune Brainstorm Tech conference, HP Personal Systems Group VP Todd Bradley said that the Slate will be "more customer-specific than broadly deployed." Seems that news is also changing so who knows what other news will be coming.
Engadget has received confirmation from HP that Windows 7-based HP Slate 500 is still in the works. News has been going around that HP abandon Windows 7 plus they were posting an Android-based tablet with the latest news being that they are implementing Palm's WebOS including filing "PalmPad" as a trademark.
HP even had the Slate 500 listed on their site which has now been taken down. However, you can click here to see a cached page. Scroll about half way down and you will see about 8 different versions.
The specs appear to be Windows 7 Premium, 1.6Ghz processor (probably Intel Atom Z530), 1GB of memory, and 2 cameras.