If your XBMC device has Wake On LAN capabilities then you may wake up your device using XBMC Touch's Wake On LAN feature. Wake On LAN appears when you press XBMC Touch's power button (look for the standard on/off icon on the lower bar just left of center). This power button will show normal power actions when your XBMC device is connected, but switch to Wake On LAN when your device is not connected (i.e. asleep and listening for the Wake On LAN packet).
1. Set up the connection to your XBMC device normally (using XBMC Touch's Location settings under the gear, top right). If the setup is successful, the MAC address will be stored for later use in Wake On LAN.
2. Let your XBMC device go into sleep mode (via Suspend, Hibernate, timing-out, etc.). XBMC Touch should change to "Not connected" (the gear in the upper right will be red and the location will be set to "Disconnected" (lower left).
3. In this Disconnected state, XBMC Touch will change the behavior of the power button to Wake On LAN. If the app was unable to recognize the XBMC MAC address, then the power button will simply flash when you tap it and not show Wake On LAN.