rear right wheel bearing on 2003 Toyota Highlander

rear right wheel bearing replaced May09 - now Toyota says it needs to be replaced again

waring noise coming from right rear wheel, becomes worse when making right turns

2 answers
As you turn the car side to side, the weight of the car loads the bearings. If you have a noise on right hand turns, look for a problem in the left side bearing where the weight shifted to. Also, cupped tires can cause noise like this. Swap the tires front to back and see if the noise follows the tires.
If you had this replaced at a Toyota dealer, their parts and labor are garanteed for 12 months so you should be able to have it replaced for free.