This is one of those neat ideas that is just the starting point for how this could really be used. The main problem is that it's a line of sight technology - clouds or other obstructions equals plane crashing to ground! It's sure fun to see stuff like this and wonder where the technology will eventually go.
Interesting article. I would imagine as batteries (like Lithium Polymer) advance, it will become feasible to add onboard to allow extended flight. For example look at how small some of the Nokia batteries are that provide days of standby time.