How-To #20: Connect PS3 Controller to Android Emulators
With Android 3.1, USB Host Capability has been brought to the Android. What this means is that many USB peripherals can now be plugged in and used with Android 3.1 devices. The people at Booya Gadget has demonstrated how easy it is to use a PS3 with a Xoom Tablet.
Note that although Honeycomb brings support to standard HID devices, the PS3/xBox360 are nonstandard HID devices so the lib files for the drivers must be loaded in the build of the ROM(i.e. the OS build). Those unlucky people with OEM roms without the non standard HID driver support on their Android must get a custom rom with the preload lib files. Personally, I wouldn't mess with loading the lib files unless you know what you are doing with linux and Android ROMs.
Additionally, the Android device must also have USB host enabled in the hardware(this is already done in software). Some devices, like the Samsung Galaxy 10.1, requires the purchase of USB host enabled adapters.
As always, if you are unsure if your Android has the necessary PS3 drivers or USB host enabled in hardware, it doesn't hurt to plug the PS3 to it a try. If all else fails, purchase a Wii controller.
Update: If you have root access and if your Android OS does not have the loaded .lib files then check out this program: Sixaxis Controller. You may want to run the Sixaxis checker before buying the program to see if it will work on your device. Read the Sixaxis instructions to get started with the app.