A "NUC" can be anything from two frames to eight frames. I believe Jack is talking about Starting Nucs..
Wiki =
Nucs, or nucleus colonies, are small honey bee colonies created from larger colonies. The term refers both to the smaller size box and the colony of honeybees within it. The name is derived from the fact that a nuc hive is centered on a queen, the nucleus of the honey bee colony.
http://en.wikipedia.org/wiki/Nuc I have started nucs with a single frame worth of bees and a virgin queen from a cast, but it took considerable resources to get it up and going. A Nuc that is considered for sale, and one that is "started" from a split, swarm, etc is very different.
In this case, I have seen folks claim to have "started" up to 4 nucs from one package. As stated, having started nucs from small swarms or casts, I wouldn't recommend the practice, without having other resources to put into it, at which point, your better off growing the package and splitting it when its strong.
I like to "start" a nuc with four frames of bees. Preferably all with brood and food, along with the nurse bees on them, and one frame of drawn comb.. It takes Covering bees to keep brood warm. A queen will not normally lay more eggs than she has bees to cover, so starting with FEW bees means it will take her much longer to get started and build the colony up. The more bees the more brood, the more bees, etc...