those of us who are addicted to TT and check it 6 or 8 times a day (or have it as a homepage :) ) noticed that it was gone and one line of incoherent text was in its place for a brief period of time yesterday.
They are a group of hackers from Brazil who use the name Rebellious Fingers. What I've read of their exploits shows them to be a nondestructive type, in that they do not destroy data etc.. They substitute the front page with a reminder that they have been in and were able to defeat the system. It seems that they enjoy exploiting the weaknesses of some server systems. This does at least expose the weakness so patches can be crafted and hopefully prevent intrusion by individuals with a more vicious intent.
I believe they pulled the same stunt about a week ago.