Now we know why 17-year-old Miley's been clubbing until 2 in the morning and why she was grinding with her Last Song director Adam Shankman back in May at the film's wrap party -- it was all research for her new music video!

In the newly-released Who Owns My Heart clip, Miley throws caution to the wind and lets loose in a sexy, steaming, grinding, pumping, tousled-hair club video fit for Madonna, circa 1989. Not a girl, not yet a woman? Eh uh, Miley's a full-fledged club creeper dancing with boys and girls; throwing kisses left and right; rolling around in bed with that come-hither look; singing, "Keep provoking me; keep on roping me!"

What can we say -- we love the video and we think Miley is DEFINITELY here to stay. What do YOU think?