Turns out it's more complicated. The LAT writes that the tabloid was right about SATC3, they just got the size of the screen wrong. Apparently, the next installment will be a TV show, not a movie.
The prequel would look at Carrie Bradshaw's life in high school, and be based on two of Candace Bushnell's more recent novels, "The Carrie Dairies" and "Summer in the City."
Whether or not the show makes its way to us, it doesn't seem to have the blessing of several members of the original creative team. Sarah Jessica Parker, who played Carrie in the original TV series and the first two movies, isn't fond of the idea of going back. Neither is Michael Patrick King, the series' creator, who calls the prequel a way of making Carrie "less evolved."