Following these factors, "share-ability" and quality of content as perceived by your human traffic are the next most important factors. Although Google's algorithms approach the level of ‘artificial intelligence’ they still have some ground to cover, as can be demonstrated by the continued success of grey-hat and black-hat SEO activities. To this end Google is constantly changing the game.
From a strategic standpoint, content managers and producers would be well served to observe the guidelines that Google promotes. Content should be original and creative, and designed for readers rather than bots. With the continuous updates to Panda and Penguin, those that utilize practices designed to “fool” the system" are playing a game of SEO chicken, that they are sure to lose over time. Quality content, quality links, and relevance to readers is a strong strategy that will stand the test of time (and algorithm updates). Lower quality practices designed to take advantage of flaws in the ‘system’ may enjoy short-term success, but result in being ‘un-indexed’ from Google (as well as possibly Bing and Yahoo) with dire consequences.
In short, content really is king, and if you want your content, your website and your other online properties to sport the crown of high-organic results and viral social sharing, observe these aphorisms; provide content that informs and educates in an approachable way. Embrace humor and humility, while still seeking to be a subject matter expert, a true authority for your audience and contemporaries. Make your content interesting, and write for the sake of your human audience, but be knowledgeable of the shadow audience of algorithms that hold sway over your reach and help to determine the popularity of your content.
Lastly, while metrics are important, proper context for your metrics is crucial. A small devoted, responsive following is far more valuable than a large disengaged following. Building community around your brand is the best way to turn your customers into evangelists.