It looks like this fight is scheduled for march 3rd (UFC 68). Here's the explanation from mmaweekly:
"Note: Tim Sylvia's opponent was originally scheduled to be Brandon Vera, but Vera was unable to come to terms with Zuffa on a multi-fight contract extension in time for this bout, and Vera is not going to get a title shot with only one fight remaining on his UFC contract."
Still, I do expect Vera to eventually come to terms with Zuffa soon. Also, I expect Sylvia to dominate Gonzaga (probably by first or second round KO).