Mark Zuckerberg hinted at this functionality at TechCrunch's Disrupt conference last fall:
Search is interesting. We do on the order of 1 billion queries a day and we’re basically not even trying. Today with search, the vast majority of it is people trying to find people, but there’s also a meaningful portion of queries where people are trying to find Pages, brand Pages, other business Pages — so there’s a bunch of that that actually does link to commercial behavior, and I think there’s a big opportunity there and we just need to go do that...
Though the initial rollout is not necessarily commercaily-focused, let's look at the potential for ecommerce marketing.
Boosting word of mouth
Someone who wants to buy a gift for their teenage niece who may search "What brands do friends of Jacqueline like?" for ideas where to shop.
Merchandising and persona research
An ecommerce marketer could discover what people who like [brand, product, etc] also like, to merchandise emails and home pages, brainstorm cross-sell associations or develop marketing personas.
Facebook advertising strategies
Facebook ads let you target by interest keyword. Discover keywords by searching "Brands that people who like [your brand]" also like," and target your ads to users who like those brands (or interests, music, TV shows).
Elastic Path's HR manager could search "friends of friends who work at Elastic Path that like Java."
Facebook Graph Search Optimization
The best way to optimize for Graph Search is to simply get as much of your content in the social graph. Beyond adding Like buttons to your home page and product pages, update your fan page frequently with posts that provoke sharing (see our post on Facebook News Feed Optimization for ideas). Explore non-product page content marketing (stay tuned for an upcoming post on content marketing for ecommerce). The point is, get site visitors to share the heck out of your content if you want a chance to be found.
Potential derivative products for businesses
Going back to Zuckerberg's comment on commercial queries, future updates to Graph Search could potentially include the ability for Business Page administrators to query the social graph of users who've liked their Page.
Facebook could also explore native advertising options like promoted search results. For example, if your brand appears in search results, you could pay to have it highlighted or ranked higher (with disclosure, of course).
Advanced fan marketing could enable a business Page administrator to query which fans like a certain TV show or event and send permission-based Facebook Messages to these users with offers (e.g. Coachella style offers, or pre-order Halo 5).
There's a lot of potential for consumers and marketers, but the big question is, do Facebook users care about Graph Search, or is this just Facebook's attempt to do something search-y that fizzles out?