My initial response to such technology is highly positive.  It reminds me of an article in Salon.com last month which discussed how Los Angeles was specifically creating wetlands on old waste land sites, and using them as natural sewage treatment systems.

However, I do wonder - where does the fuel oil end up?  Is it concentrated in some end biological organism?  Does it end up as sludge at the bottom of the restoration tanks?  Is it digested and broken up by the process?  What exactly happens to it?