swishing sound... bad?

Today this sound started on my truck. It comes from the driver side rear wheel when I take a corner. just swish swish swish... but not when going straight. Anyone offer some advice?

maybe a wheel bearing

Probably a wheel bearing or possibly something on your breaks. Go to a vacant parking lot and make it start swishing and swerve back in forth (like a Mike Jones video) and if it makes the noise and then goes away then makes the noise its a wheel bearing!
Mike

Thanks for the replies. I'll hit up the high school parking lot after work. The other side just had work done. I would definatly be taking it back in for them to look at this. But looks like this isn't related to any of that. Have to look at my Haynes manual when I get home for lunch to see what I may be up against. Thanks again!

is your truck bagged? maybe something came loose like a link bar and your axle is moving to one side causing a tire to rub.