"Of course, it is possible that the PS3 is completely secure. However, this is somewhat unlikely."
Nothing is hack proof, but the ps3 is tighter than a snail's behind. I usually expect devices that have a small following wont get hacked since the less people use it, the less likely you'll have a hacker amongst them. (iirc Minidisc's crappy DRM was never hacked for example).
With the Ps3, you have 10's of millions of people world wide using it, sure the 360 has more (and a years head start), but does that really explain the 360 being almost completely compromised versus the ps3's almost complete lack of progress? This leads me to belive that those who are trying to crack it aren't getting too far.
It took several years for progress to be made on the backup front on the 360, and that didn't even allow for any sort of "hello world". Years on with the ps3, there's no swap trick, no game save exploit etc. If there were a way I think it would have been found by now.