Sorry I missed this one

I would HIGHLY suggest using a softbody curve(s) for this effect, as that is one of the reasons it exists.

Too much to explain here, so I would suggest you check out the docs regarding learning about softbody curves AND GOALS.

Basicly, once you read that stuff, and play around with them, you will notice that if you draw a curve from the ground up, make it a softbody with "make copy soft" THEN you can weight the curve particles closer to the ground so that it does not "sway", but the rest of it can sway however you like the closer you get to the top of the curve.

Then just extrude a circle up your original curve to make some straw-like geometry, and it will follow the animation dynamicly

You could also use PaintFX for this as well because some brushes are already setup to animate like this out of the box.
(or CAN, depending on how you look at it)