The other possible clue is that they seem to have added "The challenge continues" to the home page sometime in the last few days e.g. see http://www.guardian.co

The other possible clue is that they seem to have added "The challenge continues" to the home page sometime in the last few days e.g. see http://www.guardian.co.uk/media/2011/dec/01/gchq-computer-hackers-ad http://www.guardian.co.uk/media/2011/dec/01/gchq-computer-ha... for how it looked on or before 1st Dec.