It appears that the puzzle has been pieced back together following Rory MacDonald's withdrawl from his UFC 158 bout with Carlos Condit.
Initially the UFC made the very smart move to bump Johny Hendricks up into a bout with Condit. But moving Hendricks meant leaving his original opponent, Jake Ellenberger, without an opponent. But that has now been addressed as well according to MMA Junkie:
Former Strikeforce welterweight champion Nate Marquardt (32-11-2 MMA, 10-4 UFC) will meet Jake Ellenberger (28-6 MMA, 7-2 UFC) at UFC 158, a source close to the event told MMAjunkie.com (www.mmajunkie.com) on Monday evening.
Marquardt fills a spot left vacant by Johny Hendricks, who was tapped to meet onetime UFC title challenger Carlos Condit when Rory MacDonald was forced to withdraw from the event due to injury.
Marquardt was once famously released from the UFC with guarantees from Dana White that he would never be back. But he was eventually back under the Zuffa umbrella fighting for Strikeforce, winning their welterweight championship.
He did lose to Tarec Saffiedine in the last ever Strikeforce bout, dropping a wide decision and his title with it. But this is a fine chance to bounce back from the loss and make a statement in his old stomping grounds.