It's just a faster bus, not a faster drive. So there really isn't much we should be concerned about yet. It's sorta like when PCI-e x16 2.0 came out I guess.
Is the 3.0 interchangable with the 6.0? I am looking at a motherboard that has three 6.0 ports but doesnt say if it has any 3.0 ports... so will it work with my 3.0 hard drives/