On Thursday, October 22, 2015 at 10:00:09 AM UTC+3, krasw wrote:
Several legacy variometers have had electric compass options since 90's. Instant wind speed can be calculated with TAS, GS, track and compass reading.

Instant headwind/tailwind component, yes.

Side gusts are unknown until either the glider equalizes with them, or the pilot uses the rudder to bring the yawstring into the middle (which will change the compass reading and TAS).

Now, if the yawstring angle was an input to the computer...

(or, better, a weather vane in the free flow .. maybe a nice addition to the TE probe? Or use multiple suction holes at different angles, with individual pressure metering)