Jerry Yang began his biggest public presentation since becoming chief executive of Yahoo with something of an apology.

“I’m guessing that a lot of you are here today to see what the new look and new face of Yahoo is all about,” he told an audience of some 1,500 technology enthusiasts at the Consumer Electronics Show in Las Vegas last week. “Well, I’m sorry to disappoint you. It’s still the same old face. I’ve been around since the beginning.”

Mr. Yang, a co-founder of Yahoo, was picked last summer to run the company in part to end a string of disappointments for Yahoo shareholders. Before his keynote speech was over, Mr. Yang had offered the audience and shareholders a glimpse of what may one day be the new face of Yahoo  a revamped set of online services that company executives hope will help turn around Yahoo’s fortunes.

But it was only a glimpse. Mr. Yang displayed a prototype version of Yahoo’s popular e-mail software that had been transformed into a powerful communications hub.