lynxgeek:
Let me join guys.........
I am eager to learn the embedded systems and combining them with mobile technologies ....
There are a couple of options when you'd like to go for integrating SmartPhones and Electronics (read Arduino). Broadly, Wireless and Wired. Wireless would be very easy as you can easily interface a bluetooth module with and Arduino and have the SmartPhone sending/receiving commands with/to the Arduino. For trying this out, a basic Arduino UNO will suffice.
If you're interested in a wired (USB Host connection), I'd recommend you get yourself an Arduino ADK Mega board that will allow your Phone to send/receive commands through the USB port. Do note that all Android versions donot support the Android Accessory feature (most upwards of Honeycomb will and also 2.3.7, I've a Nexus 1 on which I've tested this).
If you've any query or need sample code, feel free to IM me. Cheers! 