According to UFC.com:
UFC.COM will feature the official announcement at 1pm EST. Look for video highlights of the press conference featuring Dana White, along with a special guest, making the announcement later in the day.
Sam Caplan thinks it could be Mark Coleman. MMA Junkie is claiming the UFC is announcing a new blue chip sponsor. Personally, the UFC has a habit of misdirection when it comes to announcements large and small. For sure this isn't a television deal since I can't imagine trotting out some NBC or FOX executive is worth anyone's time. I suspect Junkie's on to something. As for the sponsor, which blue chip company also has a recognizable front man?