"Necessity is the mother of invention" is one of my favorite quotes.
When things get tough, as in our current economic situation, people find creative ways to get by. Often times time means turning to crime, and becoming creative. This was clearly the case when a fake parking ticket scam was used to direct people to a website that installed a fake IE BHO (Browser Helper Object), which then tried to get you to install fake anti-virus software, as has been the case in many instances before.
The goal, as always, is to make money on you. P.T. Barnum said it, "There's a sucker born every minute"... and these people capitalize on that. Don't be a sucker.