While it is far from the most convenient option, it is correct that Malaysian has a free upgrade program, rather along the lines of ConnectFirst by Northwest.

If you purchase a full-fare business class ticket, you are seated in First Class. Also, I think if you buy a full-fare eco class ticket, you will be seated in business class. I'm not completely sure about the latter.

Up until very recently Malaysian ran many, many ads in New York Times Magazine et al advertising this promo.