We're going to take this one from Macrumors at face value. Apple registered iSlate.com through their third party domain registration/hiding service Markmonitor.com in 2007 when it likely purchased the domain from a company called Eurobox. There were a few weeks in 2007 when Apple was the domain holder.
Remember, Bill Keller, Executive Editor for the New York Times, let slip (At 8:33 in the following clip) that:
"I'm hoping we can get the newsroom more actively involved in the challenge of delivering our best journalism in the form of Times Reader, iPhone apps, WAP, or the impending Apple slate"
