If their so good at hacking i.e. "look what I can do", why not turn their talent to do some good like developing a few B4PPC app's and then they can share them with us if they want to show off.
Is there a possibility that any of the code samples or app's could have been infected with a virus etc. It's just that recently my ISP was attacked, along with stealing a load of email addresses, a Trojan was also planted in a jpeg file.
The vBulletin experts thought that the forum itself wasn't been harmed.
I don't think that it is possible to add a virus to the source code files.
However it is recommended to check for viruses with all other files.
Something similar happened to my main website about 3 years ago. Some friends of mine managed to track the group down and in return, DOS'ed their site which was down for weeks hehehe. After that, I have never had any problems.
Btw, it was a Russian group that "painted" my site back then.