Does anybody know of a small weather sensor that will either trasmit or log weather info from the phantom?  I get asked often if the DJI app gives information on air temperature and wind speed.  It would be fun and interesting to stick a small device somewhere on there to see this kind of info.  

Well, that's a new one.  Basically no.  Weather balloons are much better suited for that sort of thing.  Considering all the spinning propellers I doubt you would get any accurate reading of wind speed.  I suppose you could get a little wireless weather station from Walmart and mount it on a Phantom for the temperature.