Bizarrely, the iPad can handle up to 11 points of contact on the touch screen and interpret them successfully, leading to some interesting games.
Android devices don’t have a unified limit on how many fingers they track. Instead, it varies from device to device and can be anything from two-touch on older devices to five fingers on some newer devices.
Any theories, however clever, on how one might fudge extra fingers on the Android?
The SDK allows for the query of any number of inputs (up to the largest value an int can hold) so any limitations would purely what the manufacturer implemented on the hardware/os end. In most cases for high end phones, it is most likely an OS limitation since touch sensors like the maXTouch in the Incredible and Evo have no limit. The NDK did add support for touchscreen input in the Gingerbread release so there may be a way to do this without custom roms. On a side note, if you need that many points, you can add the tag in the Manifest to limit your app to devices that support five or more with the android.hardware.touchscreen.multitouch.jazzhand feature tag.
It should depend on the hardware design.
Look this patent by Apple: Apple Wins Patents for iPad Dock, MacBook Air & Multi-Touch
It explains (a little) the multitouch processing for iPhone/iPad.
I highly doubt you will be able to track extra touch points on Android using the SDK, maybe, just maybe the NDK has the ability, but im almost sure you require customs roms.