As to my previous question about connecting ADXL345 with Netduino wireless, I found this project which seems that they managed to make this happen. see this link: My link
I don't understand what is mbed, and code seems not in C# :S
On that project there are 2 "parts":
-rover with mbed+xbee+power wires
-controller with mbed+adx345+xbee+power wires
Now, what I think you are trying to accomplish is:
-take measurements using adxl345+wireless transmitter+battery powered
-netduino receives data and sends it to computer=>netduino+wireless receiver+usb powered
Since the adxl345 talks SPI and I2C, you will need a microcontroller to interface it with your transmitter OR a transmitter with that functionality built in. Popular wireless transmitter(transceivers actually) are the xbee and the nrf24 devices from Nordic. In fact Nordic has some SoCs that already contain a programmable 8051 microcontroller.
On netduino's side, you will use the corresponding receiver and you can have it transmitting data to your pc via virtual serial port and powered using a 5V FTDI cable. Note that you will still need Netduino's built in usb connector for debugging and deployment using this approach.
I hope to have cleared some of your questions.