Locally, everyone's been obsessing with this story over the last few days.
Not being overly familiar with the technical side of things, all I really know is that they have SIMS running on an RM CC3 Network, and have just launched their Hosted SIMS Learning Gateway (which is now suspended).
I find it hard to believe that any pupil would manage to compromise a piece of software like SIMS, it's pretty professional software.
From BBC News - Colwyn Bay's Eirias school 'hack' claims investigated
A quick search for the hacker's quotes leads you to the original posts on the hacking forums and their screenshots of what is definitely SIMS data and a report (and is real).