In case you are interested...
Lonelygirl15 is a New Zealand actress called Jessica, apparently. According to some article she's a 19 year old actress who moved to California to get work. The makers of the "work" are a bunch of independent filmmakers, but I'm sure all will be revealed soon enough.
Image search on google came up with these pics

The thumbnails linked to a talent management agency in New Zealand, but the original pics have been taken off their site... unsurprisingly... in an attempt to hind the real identity of "Bree".
I feel a tad disappointed now the truth is out - it's like a book you just want to get to the end of to find out what happened - so you skip to the end and read the last few pages and then just feel annoyed with yourself cos there's no point in reading the book anymore. I think they should have kept the whole saga going for longer.
My addiction to/ interest in this virtual soap seems to have dissolved- which is good in a way. Less distractions the better for an ADD-type like m'self.
Anyway.. that's enough rambling for one day.

Here's a Wired article about all this.