How can I test to see if my touchpad is supports more than 2 finger gestures?

As an update to htorque's answer, you must now use geis-tools instead of utouch-geis-tools (> 12.04). So run the following set of commands:

sudo apt-get update
sudo apt-get install geis-tools
geisview

In the new window, go under Device<device_id>Added:<device_name> (Probably the last option) and check device touches: <finger_number>. finger_number will tell you the number of multi-touch fingers your touchpad supports.

You can install utouch-geis-tools and then run geistest, which shows you information about the device and gestures, e.g.:

Device 10 added
    attr "device name" = "SynPS/2 Synaptics TouchPad"
    attr "device id" = 10
    attr "direct touch" = false
    attr "independent touch" = false
    attr "device touches" = 4
    ....

where the last attribute is defined as the number of simultaneous touches the devices claims to be able to recognize.

However, uTouch doesn't seem to recognize more than two fingers on my system (ThinkPad T510), because geistest always shows

    ...
    attr "gesture name" = "Tap,touch=2"
    ...

when doing three or four finger taps, but I don't know if that's a hardware or software limitation (I just made this a bug report).

Touchegg from http://code.google.com/p/touchegg/ lets you use multitouch gestures

If it works correctly (it doesn't on my end) it should let you test how many fingers you can use.

(by the way, if you just want to know if the touchpad supports multitouch, why don't you just check the specs?)