My friend Steve over at UMPCportal.com has been into solar-powered computing for quite a long time. Being the kind of person who prefers actions rather than words to make a point he went on a 10-day bike-tour last year where he only relied on solar-energy to charge all his eletroic devices and he even finished with 80min of battery life.
This time 'round he is talking about hosting one of his Web (see?!) sites on a solar-powered Web server. He's planning on using a Raon Digital Everun S6S which consumes ~6 watts in a worst-case scenario.
It will certainly be interesting to see how it works out. As with many things these days I'm also interested in the results in the large context of the OLPC project as solar-powered servers are certanily something that could be very useful for the deployments in Peru, Nepal, Uruguay and elsewhere.