This is not a new problem. I remember in the mid-70's having to separate inbound IFR flights from glider competitions. There is also this case in the US:
http://www.ntsb.gov/_layouts/ntsb.av...6FA277A&akey=1 Hawker 800 collision with a glider. Sounds much the same Hawker IFR in descent and glider VFR.
There are simple battery powered beacons that could be used that would at least alert the powered aircraft TCAS.