Meet Dirty Sexy Money’s new gazillionaire-Blair Underwood.ABC has been saying that his official debut playing Simon Elder won’t happen until next week, but sources tell me his big reveal is actually tonight.So, who is the mysterious Mr. Elder? Underwood has been sworn to secrecy, but he did give up some details when I chatted with him earlier this week."He’s the third richest man in the world," Underwood said. "He was raised in Russia, but he didn’t grow up with money. He’s an inventor."Underwood, however, will not be speaking with a Russian accent: "He was raised there, but he’s also very worldly."Elder is also the nemesis to Tripp Darling, the patriarch of the superrich Darling clan played by Donald Sutherland. "I see Simon really as a chocolate version combination of Richard Branson and Steve Jobs," Underwood said. "But really more like Branson than anybody, because he has a very youthful energy, is an incredible visionary and he’s also very environmentally conscious and philanthropic." (P.S.: My TV diva cohort Kristin Dos Santos reported just last week that Elder is into yoga and that he and the Darlings go head-to-head in a battle for real estate.)Meanwhile, we’ll also be seeing Underwood on two other series in January. He’s reprising his role on The New Adventures of Old Christine, and he’s featured in the new HBO miniseries In Treatment, which follows the patients of a psychologist played by Gabriel Byrne.

Underwood plays a navy fighter pilot who bombs an Islamic school that kills 16 children. "His whole thing is, ‘Look, I don’t have any guilty feelings about this,’ " Underwood said. " ’I did my job and hit my target. That was my mission, and I did it.’

"He’s initially urged by his friends to go see a psychologist against his will," Underwood continued. "But he wants to go back and see that bomb site-just to see it. Obviously, there’s a lot going on there."

To hear more on my chat with Underwood and what he thinks of the Sex and the City movie (remember, he played Miranda’s love interest, Dr. Robert Leeds, for a few episodes), click here for my Planet Gossip Now video blog.

'E'