JPL completes mockup of Spirit, to test extraction procedures Answered
NASA/JPL released a cool picture today, showing their engineering rover embedded in sand with a rock underneath. This is as accurate an emulation of the Spirit rover's situation as possible. The mockup will be used for designing and testing procedures for getting Spirit unstuck and moving again (or for determining that it can't be).
NOTE: I'm not able to upload images for attachment to this topic (see my bug report). If that gets fixed some time soon, I'll update this.