No that's not my understanding of it. A dedicated bus for each DIMM would mean that a typical PC with 4 x DIMM slots would have quad channel memory. There are PC's with quad channel memory but they are very high end.
A dual channel memory controller (for example, the integrated controller on a Core i5 processor) is considered to have 2 x 64bit memory buses. A triple channel memory controller (for example the MCH on a Core i7-960 processor) has 3 x 64bit buses. Each bus or channel on these example processors supports up to 2 x 64 bit DIMMS (4 or 6 in total respectively).
Dual Channel memory controllers are memory controllers where the DRAM devices are separated on to two different buses to allow two memory controllers to access them in parallel. This doubles the theoretical amount of bandwidth of the bus. In theory, more channels can be built (a channel for every DRAM cell would be the ideal solution), but due to wire count, line capacitance, and the need for parallel access lines to have identical lengths, more channels are very difficult to add.
BTW what is the purpose of the question? General interest or is there a question about a specific system coming?