If Apple does have two separate iPad releases in 2011, I definitely think the first announcement will replace the current iPad and the next announcement will be a product that augments the iPad line, an HD or Pro model, as Gruber predicts. But I sincerely doubt there will be two different iPad announcements this calendar year. Ever since Gruber's initial review of the iPad, I've been intrigued by the possibility of a…
While better specs certainly never hurt, I've never heard any iPad users complain processing power or RAM. iOS does memory management seamlessly (if I didn't understand how it worked, I probably wouldn't even notice it) and the interface is notably responsive. I'm sure the new version will have a spec bump. Whatever that ends up meaning (dual core, faster, more RAM), it will continue to be plenty.
But that's still pretty anemic, as jonhohle noted: that's not enough to keep a lot of pages in Safari's cache. (Though, from my experiments, Safari/WebKit is REALLY aggressive about minimizing memory usage, perhaps even stupidly.)