A little over a year ago, I wrote about Facebook's new vanity URLs and the immediate SEO boost that ensued. Quora recently opened up their content to Google... and it appears as though it too is the beginning of an SEO boom. It makes sense considering how deep, rich and unique Quora's content is - which to Google is a goldmine. Furthermore, the questions and answers format has always been relevant to search engine queries. Two great examples are Ask Jeeves (now Ask.com) which was built with this in mind and Yahoo Answers, which for years has ranked terrificly in Google.
SEO has emerged from a talent (usually buried within the organization) to a business. Folks like Demand Media have turned it from art to science - and for folks like Quora, it can be an important lever for traffic acquisition, findibility, etc. Ultimately, it boils down to the lasting value of the your site's content - and Quora (and others) are in a great position for that because of its community and the dynamic nature of site (content evolves over time - it is not a static, one-time piece).
Here is a simple example of just using my own name as a query. Within a week Quora has emerged on the first page... which is impressive: