No, Sean Connery has not joined Indy 4
16/05/07, 4:43pm EST

In the article New Haven Register announced the Indy 4 shooting in New Haven yesterday, they wrote the following:
"I really have no details on it at all, except to say that there will be some filming there," said Marvin Levy, a spokesman for Spielberg, who did confirm the film will be the next in the series starring Harrison Ford and Sean Connery, set to open May 22, 2008.

The New Haven Register indirectly misquoted Marvin Levy here by alleging that Sir Sean Connery will be in Indy 4. At this moment, Connery does have the script but he has not officially signed on.

I'm mentioning this now as this incorrect story has already been picked up by German film magazine Widescreen and other websites.