An eclipse plugin would be welcome. At least something to check syntax and other simple things. Having to upload scripts to the Player, only to be caught by a missing parenthesis or a misspelled variable name will get frustrating after a while. Maybe the eclipse plugin can do the upload as well.
As for the secure key storage -- maybe an emulator could communicate with the Player for that portion? I realize the SDK was just released, but with modern development environments, it's a bit archaic.