My app makes certain date/time checks and it would be useful to be able to set the timezone for the emulator in the Android Emulator Plugin's configuration.
A more generic solution could be to configure a list of properties (with values) that are set after the emulator has booted.

For now, as a workaround, I do "adb -s ${ANDROID_SERIAL} shell setprop persist.sys.timezone 'Europe/Amsterdam'" after the emulator has booted, and before my app is installed and runs its tests.