Toyota is pretty lazy on engines, so they use the same engine in as many models as they can. the one exception being the 09' RAV's.
the V6 is toyota's 2GR-FE that they use in EVERY current-model V6 FWD/AWD car/SUV from the Avalon to the Highlander.
the 4-cyl is the 2AZ-FE, also well used in many toyota vehicles, such as the Scion tC, RAV4, Camry, Highlander, Etc. the AZ engines are currently the most common toyota engines right now, with the 1AZ being used in some of the smaller cars, and the 2AZ being used in the bigger ones.
the exception being the brand new AR-family of engines. the brand new 2AR-FE 4cyl engine being used in the new 09' RAV's is a brand new engine, and so far the RAV is the only vehicle to have one. that is sure to change with the release of the new toyota Venza, but I guess we will just have to wait and see.