The main idea is to make the interfacing between the computer and the micro-controller board wireless. It is important to know that there are quite a lot of very cheap different types of off-the-shelf wireless modules available. Many of these modules provide simple serial communication protocol the RS232 over a wireless protocol. For an example, such Bluetooth module can provide serial communication over Bluetooth protocol. Similarly modules providing Serial communication protocol over Wifi and RF are also available. Let's take an example of Bluetooth protocol for making the home automation system wireless.

1) For the micro-controller board: You can get one of the Bluetooth modules with Serial interface and connect the RX, TX and GND pins to the micro-controller serial interface pins. You need to take care of the voltage levels while interfacing with the micro-controller or a micro-controller board, most of these wireless modules can work with 5 or 3.3V.

2) For a PC you could use a Bluetooth-USB dongle that emulates serial port over Bluetooth. This means when you connect the dongle to your PC, it will show up as a Serial/COM port. Then it is quite simple, you can use the same 'C' application and same speech recognition software as mentioned in this project to send command to the Bluetooth dongle via the emulated COM port thus making this home automation system wireless. Very simple.

I leave it upto you to find out various ways to control this home automation system with countless Bluetooth enabled devices.