Here's the backstory: two years ago, the Discovery Channel put out an impressive commercial called "I Love the World." It led to many imitations, foremost among them was xkcd's version, laden with references to that webcomic. This version was then recently mashed-up by an assortment of famous bloggers.
Are we up to speed now? Good. If you're still confused, think "Internet meme starting to peak", and you've got the gist of the situation.
Speaking of Internet memes, I'd say that this Hitler/Downfall video represents the fulfillment of that meme, and hopefully its conclusion.
via reddit and Instapundit, respectively.