Based on the early photos, the larger models are a spitting image of their greatest adversary -- Apple's iPad. That's not necessarily a bad thing, though. Despite the iPad's faults, it's still a pretty piece of hardware. When asked for more details, Dell simply said it "continually develops and tests new products" and that it doesn't comment on speculation.
According to Engadget, the smallest model will be available sometime this summer, the 7-inch version will follow in late 2010, and Dell's largest tablet will appear in early 2011. On a somewhat related note, information about the Aero's AT&T release was also leaked, and you can expect that to launch this June.