Adrants observes that Engadget is running more than the normally allowed 3 ad blocks per page (I see four plus an ad unit on most individual pages and five on their main page) and wonders if it violates the Adsense TOS. Jason Calacanis answers in comments:
‘I can assure you we are not violating any terms with them.
I can not discuss the issue beyond on that.’
This either means they can do it because they are a premium publisher (because of their size these publishers can negotiate their own deals directly with Adsense on placement, ad sizes, design etc) OR that they are testing something new for Adsense (ie more than 3 adblocks per page). Of course either way they will have signed a NDA.