I've got a device (HTC Magic) with Android 2.1 (rooted, with CyanogenMod). It has Google Market app v2.23.6 - pretty old. I wonder, what's the latest version of Play that runs on Android 2.1?
In the past, this device once had trouble with updating the Market. I wonder if this is the same trouble all over again, or Market 2.23.6 is the latest I'm going to ever get?
EDIT: more about upgrading Market to Play here.
The app still calls itself Market, not Play. This might be relevant; probably Market->Play transition changes the package ID or something.