Cosmos-2 will be a very similar replacement for Cosmos-1, the first solar sail propelled spacecraft that the Planetary Society managed to develop and build from donations. Unfortunately, the very economic choice of using a Volna rocket, launched from a Russian submarine - replacing the warhead with the Cosmos-1 spacecraft - turned out to be an unlucky one. 82 seconds after launch, the engine failed and the rocket aborted.
This happened in June, 2005. Ever since, the Planetary Society was ready to build Cosmos-2. This new grant makes it possible to start the work, but they need to raise about $4,000,000 for completion.
However, the history of Solar Sails goes back much longer. It's probably no surprise that NASA did studies as far back as the 70s. But there was a already a serious proposal in 1967, called Sunblazer. It even had mockups:
It would have been a very tiny spacecraft (less than 5 kg), that would observe the Sun from 0.5 AU (using radio transmission to probe the solar corona from solar opposition). It would use solar sails, aluminized mylar foils, for attitude controls. The project was cancelled in the late 60's.
Recently, Japan had a number of solar sail experiments. In 2004, they launched a suborbital experiment, testing the deployment of two different sails (see news article).
February 22, 2006, the rocket of the Akari (ASTRO-F) mission carried a subpayload, a solar sail deployment experiment. However, the sail didn't deploy properly.
August 30, 2006, they tested deployment using balloons (see article at JAXA in Japanese).
The next experiment followed on September 23 2006. The Hinode spacecraft carried a Solar Sail Subpayload - SSSAT. Separation of SSSAT after launch was confirmed, but it likely malfunctioned.
Meanwhile in Europe...
ESA has a plan called GeoSAIL,
a solar sail spacecraft to study the Earth magnetosphere and tail. The so-called technology reference study is finished, but I don't know about the current state of the project.
I've found a short document though, a powerpoint slide titled
European Solar Sail Technology Status.
At the Planetary Society
Meanwhile in Russia... working with the Planetary Society, the Lavochkin design bureau created a solar sail experiment. Their first launch was in 2001, but it was a failure (likely cause is that the payload failed to separate from the 3rd stage). Undeterred, they expanded the film-expanding experiment into a full, 100kg spacecraft with eight 75 square meter foil blades. The launch slipped many times, until July 2005.
...and ending in another launch failure.
But now they are ready for a next go - and this time on an extremely reliable rocket instead.