Does anyone know ANYTHING about the Nielsen/NetSight software?

My girlfriend is quite certain that she did not install it, but sometime around the end of last year/beginning of this year, several pieces of software appeared on her MacBook Pro that seem to have some relation to Nielsen ratings and their NetSight software. Some of it is actual resident software on the machine, some of it appears to be some kind of Safari plugin. (The Safari plugin is called NielsenWebKit.bundle and the program is in /Library/NetSight among other palces.)

There appears to be no easy way to uninstall it, and no way to even find out what it's doing. When I do a web search for NetSight Nielsen Macintosh I find some old articles about how Nielsen is going to develop their software for the Mac, but nothing about them actually doing so, nor any support information or anything like that. There is literally no indication that anyone else has ever seen this before, except for one person on the forums here that mentions that the plugin is installed. I have tried to uninstall it, and it appears to heal itself at least somewhat. I've deleted it in four different places and think it's finally stopped, but it took a lot of effort and digging around on the computer. And it's staggeringly badly written: it ***** up lots of CPU time, it causes the machine to overheat, it leaves gigabytes of files lying around on the hard drive, and it often spews thousands upon thousands of lines into the system.log file. I can't imagine how anyone could NOT notice that this was running.

She did lend her computer to a couple of people briefly around the time it was... I want to say 'infected'. It's possible one of them installed this. But I can't even imagine where they got it from, if that's the case.

Does anyone know anything about this, not limited to: where she got it, how we get rid of it, and who we sue over it? It made her computer nearly unusable for months before I found it, and it took me weeks to finally manage to root it all out.