The last sick bastard who utilized white phosphorus as a weapon was Saddam Hussein. But now, after several initial denials, the US admitted that they've done it too
, in Falluja. Last year.
White phosphorus is a cruel chemical weapon. It burns you at about 1300° celsius. Down to the bones. If you somehow manage to escape, it is impossible to operate your wounds, because it will start burning as soon as the phosphor touches air again. But never mind, if you catched more than 50 milli grams, you'll die a wretched death after about a week anyway because it is toxic too.
In my opinion, no sane human would use such a weapon.