[Luke Hutchison] has come up with a rather clever hack to get multitouch support on the G1.
He wrote a patch against the Synaptics touchscreen driver. When two
fingers are placed, the driver reports the x/y of the midpoint and a
radius for the size field. If only one finger is used, the size is
reported as zero. The nice thing about this approach is that it’s
backwards compatible; the extra data will be ignored by current apps.
Unfortunately, Google’s Android team says that if multitouch is ever
added, it would identify individual fingers and definitely not using