It's long been expected for Steven Jackson to void his contract; the Rams moved to allow him to do so last year because they did not want to be on the hook for the final few years of his previous deal. Now, it appears that Jackson has made his decision: he plans on voiding his contract and becoming a free agent on March 12th, according to the Post-Dispatch.
This doesn't mean the Rams can't sign him, of course, to a cap-friendlier deal. That's probably the best scenario for the team, but it might not be the best for Jackson. He's long been the workhorse for the downtrodden team, and the thought of playoffs might make him look in other directions.
The Rams have been in constant contact with Jackson and his agent, so it's not like they are out of the running yet. However, with teams like Atlanta and Green Bay expected to throw their hat into the ring, it's a tough sell for the Rams against perennial playoff contenders.
That's one of Jackson's biggest interests (playing for a contender), but he also wants to stay with the only team he's ever known. If he has played his last game for the Rams, you can't help but root for such an amazing football player, wherever he winds up.