Speedometer died, then restarted...help!
 

I was driving in to work today and my speedometer go up to around 40 - 50 mph and then the needle dropped to zero (the car was still moving). It also appeared that the odometer stopped working as well (but I'm not sure). A couple of miles later, after a stop, it came back and worked the rest of the way to work!

I took the car to the track and it saw speeds I'm sure it's note used to, but I doubt that killed it.

I'm not sure what to start searching on as "speedometer" brought up 34 pages of threads. Any guesses as to what to check?