A sommelier (somm), as defined in the dictionary, is "A restaurant employee who orders and maintains the wines sold in the restaurant and usually has extensive knowledge about wine and food pairings." This used to, and recently has expanded to include other beverages, including beer, sake, spirits, and non-alcoholics.
According to my experience, this definition barely scrapes the surface of a sommelier's responsibilities! A somm is in charge of every beverage a restaurant carries- from teas to liqueurs. And this should be done in congruence with the chef, menu, and theme. The somm is also in charge of everything pertaining to the beverages: storage, glassware, equipment, cleanliness, inventory, budget, sales figures and projections, promotions, and implementation of staff wine/bev education- if the staff doesn't know about the product, how can they work with it?!
There is also the issue of "floor time". This is when the restaurant is open, and much of the somm's time is taken up attending to the guests and aiding waitstaff. This is possibly THE most important function- the guest comes first! There is no ego, no snobbery, and no cheap sales tactics. Your best somm's can speak with any guest, get to what they want, and surpass satisfaction. Some guests may be looking for the best wines, some may be looking for the best value- READ and RELATE to the guests. If a somm can do all this, they will instill trust in themselves and the restaurant while winning over the guest.
It should also be known that a sommelier can learn through study, On the Job Training, and/or classes. You can be both a sommelier through job title and a sommelier through certification (though not necessary). The certifications are great to have, and each gained are accreditations and accomplishments, but nothing beats experience. If you have the time and are interested in becoming certified, I found that both the Court of Master Sommeliers and International Sommelier Guild are reputable and worthy.
(Image courtesy of flickr)