NASA's Stardust spacecraft successfully flew past Comet Tempel 1 last night, and NASA has begun releasing images of the flyby.
The images can be found here.
Here's the closest image posted so far:
(Original source of image)
Tempel 1 was the comet that collided with the Deep Impact mission in 2005, and it appears that Stardust was able to photograph the area where Deep Impact crashed. This is the first time a comet has been visited by spacecraft on two separate occasions, so it should give an opportunity to see how the comet's surface has changed over the last 6 years.
More information is available at:
Planetary Society Blog.
NASA's Stardust Mission website .
Update: Emily Lakdawalla at the Planetary Society Blog has a summary of the NASA press conference (NASA hasn't posted it yet). The mission was a complete success, and it seems that they successfully located the Deep Impact crater, which is 150 m in diameter.