The only blue coolant that I know of comes in some of the newer Hondas, and the only difference is it's supposed to last longer than the green (100k miles vs. 60k miles). Now whether that's what's actually in your radiator, or whether it's something else (previous owner did something idiotic like put windshield washer fluid in??), I can't really say.
Your car came from the factory with Dexcool (red/orange), which certainly has a lot of critics, and has led to many issues (enough so that a class-action lawsuit was filed against GM). I'd have it completely flushed out, and just use good old fashioned green coolant.
