I would be doing the same thing you are, but I'm sure he's OK. A friend of mine had a very similar thing happen a year or so ago with her DH. She finally heard from him around lunch time, he had been in meetings with clients all morning and couldn't contact her. He had gotten to the office so early, he didn't even have to sign in so there wasn't a record he was there. My guess is your husband left the hotel before 9am to go to work. You could try the hotel and see if he checked out. You could also try to his office and see if they have heard from him. They would probably know if he didn't show for the meeting. Good luck and keep us posted! I'm sure everything is fine (but I do understand why you are upset, I'm 25 weeks pg and would most likely be freaking too).
~Ellen