According to Steve Squyres' latest journal entry, Opportunity is now seeing virtually -no- blueberries in the surface matrix anymore.

"...On top of that, Opportunity has stumbled onto something really new and different lately... the blueberries seem to be gone!..."

And a theory:

"But one possible guess at this point is that we have moved "up section" in geologic terms -- to rocks that are higher up in this stack of layered sediments -- and that the rocks at this level never experienced the concretion-forming process. It's an interesting hypothesis with interesting implications, and it's also one that could explain a few other odd things we've been thinking about ever since Eagle crater"

Looks like Oppy will stop for some intense IDD work in the next day or so.