When will Beyoncé, 26, and boyfriend of more than four years Jay-Z, 37, finally say “I Do”?

“One day soon — let’s leave it at that,”

the usually tight-lipped rapper told reporters earlier today at a press conference in Las Vegas, where he announced plans to open his third 40/40 Club at the luxury Palazzo hotel.

Would they tie the knot in Sin City?

“I don’t know,” he said. “It’s kind of comfortable here. If [Palazzo President Rob Goldstein] throws in the ring, who knows?â€?

At least they’d have somewhere to celebrate: His new $20 million, 24,000-square-foot club — slated to open December 20 — will come complete with 24-karat gold and platinum floors, 85 plasma TVs and — count ‘em! — five VIP rooms.

“Las Vegas is like no other place in the world,” he said.

In fact, he says he may even snap up digs there eventually.

“I’m going to ask [Goldstein] for advice,” Jay-Z said. “He’s pretty good with the real estate. We’ll see what happens.â€?