"The EPA's first test site is its Edison, N.J., facility, where the agency has replaced a 3,995-square-meter section of parking lot with three different types of permeable pavement-interlocking concrete pavers, porous concrete and porous asphalt-and planted several rain gardens (pdf) with varying vegetation for the study. (Note: Interlocking concrete pavers are often called porous pavers, although the pavers themselves are not porous.) Researchers will over time evaluate the effectiveness of each pavement type and the rain gardens in removing pollutants from stormwater, and how they help water filter back into the ground, according to the agency."
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Rain Garden PDF Link
The link provided for the rain garden pdf doesn't seem to work. Here's one that does... http://www.epa.gov/ednnrmrl/publications/factsheets/RainGardens_Brief.pdf
The APA's weekly podcast from August 13th has a great session with David Yocca who goes into more detail on the porous paver concept. Worth checking out if you're interested in the topic.