Let's not forget, it's us monkeys here that trought up mobile - not a word of that from Matt.
There are some very sneaky cloaks getting through right now - like pages that redirect the regular browser but serve 200 OK content to googlebot in order to rank and acquire fodder for whatever they're up to.
Those redirects often end up on an "Adwords-looking" page that isn't really Adwords but instead it's a part of a private ad network. And of course, the cached page is just some juicy content, often parasite hosted.
With regard to backlink values, this past fall Google did a lot of that kind of clean-up from what I see. They may show up in the link: operator results but that doesn't mean they count for anything.
Google will [look] more at cloaking in Q1 2011. Not just page content matters; avoid different headers/redirects to Googlebot instead of users.
note - he added the word [look] in a later comment
One word - AFFILIATES!
Affiliates must send Googlebot to a blank page instead of through to the affiliate site in order to control what affiliates call "bot clicks". In programs like eBay's, bot clicks are a huge concern and cause revenue loss. Is Matt suggesting Googlebot should be sent along to eBay anyway?