The Mars Exploration Rover Spirit marked it's 1,000 Martian day in operation a few hours ago, and to celebrate NASA has released a set of large panorama views online. A Martian day, commonly referred to as a 'sol', lasts the equivalent of 24 hours, 39 minutes, and 35 seconds in Earth time.
The original Spirit plan only called for it to be in operation for 90 sols, so it has exceeded its design goals by long, long shot. We're definitely impressed. The latest panorama posted on the NASA website is in approximately true color, which NASA explains by saying, "This 'natural color' view is the rover team's best estimate of what the scene would look like if we were there and able to see it with our own eyes. " They have also included links to stereo and false color images of the same scene.