Dave Meltzer of Yahoo! with the scoop:

UFC officials have confirmed that Lyoto Machida will need surgery on one of his hands, thus delaying the planned middleweight championship rematch with Mauricio "Shogun" Rua (18-4). Machida injured his hand during his controversial win over Rua during UFC 104 Saturday in Los Angeles.

Obviously Dave means "light heavyweight championship rematch."  Dana White had been trying to have the fighters do a quick turnaround and fight on January 2.  This was for a combination of reasons mainly that the New Years card is traditionally one of the biggest of the year and also that the controversy over the close decision means there is money in the fight now.

Kid Nate of Bloody Elbow brings up the odd situation the UFC has been put in due to Lyoto's injury:

Machida's injury means that four of the five UFC champions are out of commission:

• Heavyweight Champ Brock Lesnar: UFC 106 bout with Shane Carwin postponed until UFC 108 due to flu.
• Light heavyweight Champ Lyoto Machida: out for hand surgery, return date unknown.
• Middleweight champ Anderson Silva: out for elbow surgery, bout with Vitor Belfort remains unscheduled.
• Welterweight champ Georges St Pierre: torn abductor muscle, may be out until March 2010.
• Lighweight champ B.J. Penn: healthy will defend his title against Diego Sanchez at UFC 107.

The UFC is even having trouble with the health of their undercard fighters as Jon Fitch has had two opponents blow out knees in the last two weeks.  It will be interesting to see how the promotion continues to deal with the injuries to it's top end guys.

SBNation.com will have more on the injury as information becomes available.