This is a sign that water is getting into the il. This can occur from a leaking oil cooler, a leaking head gasket or some other cooling system leak that is allowing engine coolant to get into the engine.
Better get it looked at by an experienced technician, they will know how to find the source of this leak.
Bret is right on. Some condensation in the oil may be normal if the thermostat is stuck open and you only do very short drives every day where the engine never reaches operating temperature, but these engine do blow head gaskets more than any other Toyota engine!