While we're on the topic of fuel cells, and (arguably) closer to residential concerns, has anyone seen anything good or bad about Fronius' system: http://www.fronius.com/cps/rde/xchg/SID-30DD8012-93D2BF1E/fronius_usa/hs.xsl/2714_1586.htm

This fuel cell is touted as a PV buffer, presumably taking on the role of batteries in a battery backup system.  We're comparing various PV schemes to install at our house, and I stumbled across this.  Obviously, not there yet in the near term, but interesting in the sense that its main application does not require fossil fuels.