The CPU does not have an internal DDR3 controller like the AMD AM3 CPUs or the newer i3/5/7. But you will find many crossover boards that have an added DDR3 controller. For example, I have an ASRock P43D1600Twins... It is a Core 2 board with 4 slots for DDR2, and 2 slots for DDR3. You cannot run DDR2 and DDR3 together, but you can run either of them individually.
But many LGA775 boards that do support DDR3 only have 2 slots and also usually have a 4GB or 8GB limit. My ASRock board can take 16GB of DDR2, but only 4GB of DDR3. So just read the small print on LGA775 boards that support DDR3 to make sure the controller supports the type and amount of DDR3 you want.