Got this topic on the wrong board originally, but did get an answer there.
Yes, there is compostable plastic being produced and it reads "compostable" on the back side; there are no recycle symbols. So don't put it in with the recyclables, it goes in the garbage (solid waste), and will break down in a landfill.
The piece I got was a produce tray from Trader Joe's. I imagine there will be more showing up in the "disposable" stream; any other sightings?