The film in question is a heist drama called "Josiah's Canon", to be directed by Brett Ratner.
They were going to start shooting around Europe next February, but Connery has indeed quit the project to write his book. Apparently he was on $17.5m for it, which seems a bit excessive to me.
If he does retire now though, as is rumoured, then his last film would be LXG-I'm sure he doesn't want that the footnote to his career.