It depands. The 12'' alubooks never had backlight keyboard and the 17'' alubooks always had it. The 15'' alubook was available in two variations: one without a superdrive and no backlight keyboard and one including superdrive and backlight keyboard by default. The question now is, if your friends alubook has a superdrive and if he ordered this drive explicitly. If he has no superdrive (dvd-burner) then he also has no backlight keyboard.
You could theoretically order the no-SD version with a backlit keyboard as an extra. The most simple way to see whether a PB has a backlit keyboard is to look at the F-Keys. If there are function keys for the backlighting, then it has it. Otherwise not. But probably he just has the same PB as me, without backlit keyboard.