I was wondering about that as well. According to the manufacturer, the DJI Phantom[1] (a common consumer drone) has a max vertical speed of 6 m/s. So in 10 minutes (battery lasts about 20, 10 up, 10 down), you could reach 3600m. Higher than these pics were taken! (you remote probably won't reach that...)

Not sure if the max speed is up or down... [1]: http://www.dji.com/product/phantom/feature

The heck with down, it'd be interesting to try a one-way trip! I wonder how the thinner air up high affects things.

For the one way trip: https://www.youtube.com/watch?v=GfxdeRx2fLA (Not me or anyone I know, that is a pretty stupid flight).

About the thinner air... I regularly fly a hexacopter at 7500' (MSL here in the mountains).

With all other things being equal, the thinner air means you have to run the motors at much higher speeds to appreciate the same lift, and the resulting loss in battery life is pretty significant. The same configuration that gets a 30 minute flight a 1000' MSL will only do about 12 minutes at 7500'.

Model gliders soaring in thermals can exceed 2,000 ft. Since the energy is supplied by the rising air, altitude is limited only by the pilot's ability to perceive the aircraft's orientation at that distance!

above the clouds. https://www.youtube.com/watch?v=yAoSHxzEcT4

I think this is a better video of above-the-clouds flight: https://www.youtube.com/watch?v=GfxdeRx2fLA