CO2 cleaning

A friend told me about a relatively new cleaning technology. CO2 cleaning. I turned net-gopher for 15 mins, and so it turns out there are a bunch of professional laundry cleaning systems -

1. Traditional "dry" cleaning using perchloroethylene ("perc") as a solvent, which is not so good for the environment and neither for humans (perc is carcinogenic).
2. Wet cleaning, which uses water. Like at home, but the machines are more gentle.
3. Cleaning using alternative solvents such as hydrocarbon and silicone, though my quick internet reading seems to indicate clothes cleaned in hydrocarbon emit VOCs (bad), while silicone cleaning is still being evaluated for health risks.
4. CO2 cleaning, which uses a mix of gaseous / liquid CO2 as a solvent, is good for the environment and apparently produces the best cleaning results.