@Zapro, yes I know the blade only works in the correct direction- I was just experimenting with reversing the fan motor because I had one and couldn't find a normal DC "toy" motor. 
But I'm curious as to why they bother with the control electronics- buried inside a laptop where it won't get fiddled with under normal circumstances, and with a plug that prevents reverse polarity in the first place, it seems a lot of trouble or expense to go to.