ISFA installed the largest parking lot made of Unilock's permeable pavers for the US Cellular Field in Chicago. ISFA is claiming it "achieved a $400,000 cost savings compared with what it would have cost to install and maintain traditional asphalt paving...Not only does installation and maintenance of permeable pavement typically cost less than it would for poured-in-place concrete and bituminous asphalt, but it is highly durable and stronger that those materials and it lasts twice as long as traditional paving, according to an ISFA press statement." (hat tip: Philip Proefrock)
Another solution is to use an Ecogrid, which not only keeps gravel in place but helps distribute weight evenly on the parking surface. It assures filtration while preventing problems with pooling/gravel dispersement. An ecogrid can also be used for a green roof.
A less effective solution is the Eco Stone or other such pavers. It seems to me the permeability of the concrete itself is the major benefit of Unilock's paver, which will allow easy adoption by more commercial applications...and help lower landscaping costs associated with open cell systems.