This isn't new
The ability to take over command and control functions of botnets is not new, in fact early last year TippingPoints research team at DVLabs had a semi-religious debate about commanding the Kraken worm to kill itself and clean up.
http://dvlabs.tippingpoint.com/blog/2008/04/28/kraken-botnet-infiltration
and
http://dvlabs.tippingpoint.com/blog/2008/04/28/owning-kraken-zombies
I echo the first comment - its a shame that despite having the technology to mitigate these infrections, Governments throughout the World ban the action.