"[Spirit's] driving days are likely over," according to Doug McCuistion, NASA's director of the Mars exploration program, but "science will continue." Spirit has been stuck in loose sand since April of '09 and despite all attempts the space agency has been unable to free it. Efforts will now focus on trying "to jostle the rover in place and angle its solar panels to increase its chance of surviving the Martian winter." according to this CBC News story.
Spirit and it's sister rover Opportunity landed 21 days apart in January of 2004 on missions with expected lives of 90 days. Spirit, the first to land on January 4, 2004, has encountered some mechanical difficulties limiting it's movement but Opportunity soldiers on continuing to explore the surface of the planet with over 19 total kilometers on the odometer.
"Spirit is not dead," said McCuistion "It has just entered another phase of its long life."
Long live Spirit!