Looks good. I see it uses Pulse Width Modulation to control the fan speed. This was one of the alternative methods I thought about when I was first contemplating making my controller. I decided against it because I was worried about the possibility of introducing electrical noise into the system. I might still have a go at it though, just for the hell of it. Does anyone know whether this would be a problem?

Something else I noticed was that it's called a
Tiny
Integrated
Temperature
Sensor

edit I notice both of these use PWM.
edit (again) Aha, I've also just noticed that they recommend putting a capacitor in there to reduce electrical noise. Doh!!