Added in firmware version v1.1.0 - see firmware page for how to update.
To enter standby mode, press and hold the mode button for a couple of seconds. The display and audio hardware will be powered off, and the processor will enter low power mode. Press the mode button again to power back on.
All settings are currently reset to power-on defaults when resuming from standby.
Typical current draw in standby mode is a few milliamps.