oxo-degradable plastic

I’ve been hearing and reading a lot about timebomb additives for plastics that make then degrade in landfills. It was mostly for film but now I see the same claims for hard plastics:

http://www.planetgreenbottle.com/works.html
http://www.wellsplastics.com/httdocs/biodegradables.html

Does anyone have any experience with this product to back up their claims?