The media love their catchy phrases (often whether they fit or not), and one of the faves recycled every few years is how Madonna is "constantly reinventing herself". I would submit she's just super-talented. Love her or hate her (I fall somewhere in the middle), Madge has demonstrated an uncanny ability to draw headlines, fans, and dollars almost at will over her near 25 year professional career. Sure, she's had her challenges but those memories quickly fade with each new success. She has that rare ability to fuse creative talent with a keen instinct for the current cultural climate, and is very focused & disciplined with the execution. She is also very intelligent, with good street smarts.
Apparently Madonna Louise Veronica Ciccone wowed 'em once again in Lisbon recently at the MTV awards where she, as this article puts it, showed the younger stars how its done. (if you don't think of her as disciplined, look at the pictures in the article. It takes some work to look that buff at 47!)