On the dell xps 1340 laptop, the synaptics touchpad hangs upon resume from suspend. I found that this was due to the driver not waiting long enough in setDevicePowerState() for the hardware to reset. I discovered this by looking at the linux driver (that does not share this problem), and noticing that it states, in drivers/input/serio/libps2.c:
"Some devices (Synaptics) peform the reset before ACKing the reset command, and so it can take a long time before the ACK arrrives."
and so the code waits for up to 4 seconds for the ACK to arrive.
I changed the IOSleep(1000) in ApplePS2SynapticsTouchPad::setDevicePowerState to IOSleep(4000) and that has fixed the touchpad hang problem with VoodooPS2Trackpad. Been running with this fix for a week now with my laptop suspending&resuming all the time, and it has been working well.
Context diffs attached