So there are a few manufacturers - Lenovo and Toshiba - who have posted Windows 8-specific touchpad drivers for users of their laptops. Problem is you couldn't take those drivers and install them on other laptops. Furthermore Synaptics have yet to post Windows 8 compatible drivers on their site.
The existing v15 drivers on http://www.synaptics...sources/drivers
will install in Windows 8, but with one major problem - for Metro apps which aren't built on HTML+JS, you can't scroll. You need v16 drivers, like those posted by Lenovo and Toshiba above.
Thanks to this tip
the ever useful station-drivers
page does have v16 drivers, which will restore scrolling in Metro apps, and in addition grant edge gestures - swiping from the right edge for charms, left edge to switch apps, and the top edge for the action bar.
In practice the gestures don't work too well. There is a tip in this page
if you want to disable them after installing the drivers.