But who is she?

Lauren Stoner has an absolutely divine body.

Lauren Stoner models bikini in Miami  (video from USA Today and Splash)

She's an erstwhile actress and apparently was director Michael Bay's swimsuit squeeze for a short time.  I'd say he should have stuck with it a bit longer, if only for the candy factor.

If you want more information or just a lot more pictures, pretty much all the information that's available and some really nice pictures (including toplessness, if you're in favor of that) are here:

Lauren Stoner is ... ?