I came across a small article on page 13 of the July 25, 2005 issue of Aviation Week and Space Technology. It isn't available online, so I'll type the highlights here.

The European Space Agency is supporting development of a solar-powered airplane, the Solar Impulse, that Swiss adventurer Bertrand Piccard hopes to fly around the world. Design and assembly are planned for 2006 and 2007, followed by a first flight attempt in 2008. The team expects to perform its first night flight that same year (AW&ST June 27, p48). Long-range trials are to take place a year later, including a transatlantic mission and an around-the-world tour, with at least one stop on each continent. Piccard is scheduled to attempt the round-the-world mission in the single-seat aircraft in 2010.

There's more, but you'll have to get the hardcopy issue to read it (don't want to violate their copyright).

The article also has an artist's conception of the plane. It features a very small cockpit mounted below a very high aspect ratio wing. The "T" tail is mounted at the end of a slender boom. There appear to be two electric motors mounted about 1/3rd of the distance from the fuselage to the wingtips and spinning fairly large diameter propellors. The wings are covered by solar cells and there are 4 pods beneath the wings (one near each wingtip and one about halfway between the wingtip and the propellors). Those will probably hold the lithium batteries used to store electricity generated during the day for nighttime power. According to the article, the wingspan will be about 80 meters (260 feet) and will operate at altitudes up to 36,000 feet, necessitating a pressurized cockpit.

It looks like a very clever design. It's interesting that the cockpit will be pressurized, in part because it would seem that would require a fair amount of power to operate a compressor.

Here's another article with a picture. Interestingly enough, there's a completely different artist's conception out on the net in articles like this one. I understand the reasons for mounting the propellors there (less drag because the wing isn't flying through the propwash), but that would result in a much heavier tail and the need for much heavier electrical cables. I like the other design better.