Forgive me, but I do have some slight doubts here.
As has been mentioned, the stabilization gates for the approach are between 1000´ and 500´ AAL, so the decision on flap setting and approach speeds (and prop RPM on a turboprop) will be made way before this. If something untoward happens close to or below those altitudes, it will be a go around instead of a reselection of flap or other setting - and usually, a nasty gust, a windshear or whatever else will be noticed much quicker by the crew itself than it can be sniffed by any system, relayed to tower and then broadcast by whatever means.
So I think a system that monitors such small-scale weather definitely has its merits and is desirable to have. But instead of flooding crews with information on short-term changes, simply giving them a heads-up on the observance or possibility of low-level windshears or the like before they even decide for the approach and their required type-dependent settings seems useful enough.
Last edited by Tu.114; 27th August 2012 at 05:13.