Who's Watching us Online?

My softmore year of college I did some volunteer work at MADD (Mothers Against Drunk Driving).  There, they would give me about an hours worth of work with four hours to do it.  Because of this free time, I would often sit back and listen to the conversations around me.  One in particular caught my attention.  A woman in the cubicle next to me was talking on the phone, explaining to whoever was on the other end that she had been monitoring a high school student's Myspace page.  She was doing this, I learned, in order to use it as evidance for a judge to show that the student was violating his probation by drinking on the weekends.  It makes me wonder; who else is looking at our digital footprint, and will this become more common place in the future?