Just as the above poster described, concierge is an extra level of service. The pre-planning staff can assist you with a wide variety of requests such as making your advance dining reservations, booking fireworks cruises, and arranging for gifts to be purchased (with your money) and waiting for you in your room. They can also make recommendations of fun things to do and places to dine.
As far as the concierge lounge goes, they do offer food service throughout the day. Its not enough to make a meal of (except for breakfast), so dont look at it as a meal replacement plan. Its a lovely way to get some snacks in between meals and sample some nice appetizers and desserts in the evenings. Often the concierge lounge evening offerings are provided by the restaurants in that resort (for instance, the California Grill provides the evening hors devours for the 14th floor concierge level at the Contemporary), though not always.
Should anything arise during your stay, the concierge cast is happy to assist you with any last minute reservations. They tend to have pretty good luck arranging things at the last minute, but its not guaranteed to get Cinderellas Royal Table for breakfast or anything like that.
Concierge guests at any Disney resort are eligible to participate in a wildlife discovery tour for an additional fee. This takes place at the Animal Kingdom theme park. Concierge guests at the Animal Kingdom Lodge are eligible to participate in two other special safari events for additional charges. The Sunrise Safari takes place inside the Animal Kingdom theme park before park opening and includes a delicious breakfast spread at the end of your safari. During the safari itself, you are accompanied by a wildlife guide who can answer all your questions about the animals, and the jeep stops frequently for pictures. The Sunset Safari is offered in the evenings on the grounds of the lodge itself. At the end of your safari you can have a private dinner at Jiko complete with wine pairings. All of the safari events are an additional fee on top of the cost of the concierge room, so keep that in mind. They are very special events though, so its worth the cost.
Typically, concierge rooms cost in the neighborhood of about $435 a night (WL is less expensive and the GF and CR are more expensive). You can get
AAA or AP discounts on them from time to time as well.