Indeed, in the last few years we seem to have an over ubandance of sequels, but msot of the highly successful films being released lately have been franchises, this means sequels (Spidey, Pirates, X-Men, Shrek...) They make money so they make more...sometimes it's a good idea, sometimes film makers need to know when to stop.
And if you think this summer is something, confirmed for future release are: "The Dark Knight", another Superman film.
Rumoured: X-Men 4, Spidey 4 and more Shrek.