Ok - since there has been little to no developer progress on this bug for a long time, I have tried to muck through the synaptics driver source code on my own to track this problem down. I tried the patch suggested by Charlie but it did not really help. It ignored a finger on the touchpad button if it was the *second* finger to hit the pad, but the problem remained if it was the first finger down. I have made an adjustment that effectively fixes the problem on my touchpad - fingers outside the active area are ignored no matter the order in which they touch the pad. I will post my modified driver source here in the hopes that it will fix the issue for other users as well.

I have to say that the synaptics driver is a complete mess of spaghetti code (I found GOTO statements. That's right... GOTO statements!). I am very far from actually "understanding" the driver - I only decrypted enough to make this modification. The one side effect that I am aware of that results from my change is that you cannot right-click using the right soft button if you have other fingers on the touchpad already. You either need to two-finger click or remove the other fingers before right clicking. Other than that everything else works, including two-finger scrolling (onggie's suggestion sacrifices this). I do not use tap-to-click since it drives me crazy, so I have not tested this.

To apply this fix you need to replace your installed xorg synaptics driver. I will try to walk you through this here. First, you need to figure out where your driver is installed. Different distributions put it in different places. If you use Debian, the driver will be installed to "/usr/lib/xorg/modules/input" and the extra stuff will be in other places in /usr. Some ditros put components in /usr/local/..., so you need to figure this out. I suggest using your package manager to locate the xorg synaptics driver and look at the installed files - this will tell you where they are hiding.

Next, download and extract the archive I have attached. Open a terminal to the extracted directory. You need to run ./configure next, but you must pass it the installation prefix so when you install the driver it goes to the correct place for your distro. In Debian, run "./configure --prefix=/usr". If your distro stores the driver in /usr/local, then use this as the prefix instead.

Next, run "make" and ensure that it builds without error (you will probably need some dev packages installed). Then run "sudo make install". Now, you need to set the AreaBottomEdge option for the driver to define the region you want to ignore fingers in. I suggest running "synclient" and find the value you have for the option RightButtonAreaTop. Use the same value for AreaBottomEdge. This will make sure that the button region and the "active" regions butt up against each other but do not overlap. When you know what value you want to use, open the file "/etc/X11/xorg.conf.d/10-synaptics.conf" and add the option value to there (create this file if it does not exist). My conf file looks like this:

Section "InputClass"
        Identifier                      "Trackpad"
        MatchIsTouchpad                 "on"
        Driver                          "synaptics"

        Option  "TapButton1"            "1"
        Option  "TapButton2"            "2"
        Option  "TapButton3"            "3"

        #Uncomment the followings to scroll with your thumb
        #Option  "EmulateTwoFingerMinZ"  "70"
        #Option  "EmulateTwoFingerMinW"  "0"

        Option  "VertTwoFingerScroll"   "1"
        Option  "HorizTwoFingerScroll"  "0"

        #Let finger rest
        Option "AreaBottomEdge"         "1822"
EndSection

Finally, you will need to reboot for the new driver to be loaded (unloading and re-loading the psmouse module does not do the trick - not sure why not). When you reboot, hopefully your clickpad woes will be over. Best of luck!