Sienna Miller showed her baby bump last night in NYC. She wore a tight black dress to attend W magazine's "The Ever Changing Face of Beauty" event at the Park Avenue Armory, and she posed for a few pictures with the magazine's editor, Stefano Tonchi. It was Valentine's Day, but Sienna didn't bring her reported fiancé Tom Sturridge along to the event. Nor did she wear the diamond he gave her! Sienna Miller's engagement ring was on display just a few days ago, however, when she spent an evening at London's Groucho Club.