i have an AM3 motherboard and i want to buy an AM3+ CPU. Will it work?

i have an AM3 motherbord and i want to buy an AM3+ CPU. An my question is: will this be compartible? I have heard that te "ZAMBEZI" are compartible backwards with motherbords, is this information valid? If now what type of AMD cpu will work with an AM3 motherbord? Please help me here i need to upgrade my PC. Thank you in advance.