Triple channel memory is a kit of three matching DIMMs.
Triple channel memory is only useful on an LGA1366 motherboard, which typically has two banks, each of 3 DIMM sockets. That's why you see systems using LGA1366 typically having 3GB, 6GB, or 12GB of RAM (3 x 1GB, 3 x 2GB, 3 x 4GB...).
The three-way interleave is BETWEEN three DIMMs, not internal to the DIMM. The individual DIMMs are exactly the same as you see in two-way interleave between two DIMMs on every motherboard that's not LGA1366.