How successful has the Shrek franchise been for Dreamworks?  The answer can be seen in the studio's hiring of screenwriter Tim Sullivan to write the script for Shrek 4 even before Shrek 3, which is currently slated for a May 2007 release (when if all goes according to plan it will battle Spider-Man 3 in a duel of box office titans) goes into pre-production.  Putting up this kind of front money so far in advance is the ultimate expression of a studio's faith in a 'franchise.'  The first two Shrek films have raked in more than a billion dollars worldwide and established Dreamworks as an animation powerhouse after the studio's earlier efforts failed miserably at the box office.