Perfect Dark, is the sort of successor to Share which is the successor to the infamous Winny program.
I believe I have posted before about all of the arrests from Winny and Share. Now, the new kid on the block, Perfect Dark is also not a safe haven for Japanese online pirates as well, as the first arrest has been made on a 37 year old part time worker for distributing anime.
I guess he needs to read more slashdot.jp so that he would have known that the encryption for this program as well was cracked last May and that he shouldn't be using it.
If I were a developer of these illicit P2P programs, I wouldn't try to develop my own protocols for anonymity (as we all know developing secure protocols is an extremely difficult task), I would exploit something like tor to use as the backbone for providing anonymity so that the smart folks at Net Agent, the company famous for reverse engineering and breaking all of these encryption schemes, would have to then break tor.... which might be a little harder.. (and even if they succeed, I wouldn't have to worry about it anyway because I would have Roger Dingledine to fix it for me anyways =) )
(Sure download times would be terrible due to tor's lag, and overloading the network would make it slower.. but it would also be adding many fast gigabit fiber optic connections on the up side as well which might balance things out somewhat... At least users could have a little more peace of mind not having to worry about being arrested, and losing everything they have because they don't want to or can't afford the insane prices on anime here)