Let me start by saying that I have no idea what I’m doing when it comes to desktop Linux. I’ve been running Ubuntu on this new ThinkPad for less than a week, and Ubuntu 17.10 for maybe two days.
One of the first unpleasant discoveries after upgrading from 16.04 to 17.10 was that two-finger scrolling on the trackpad stopped working. This took a bad situation and made it completely unbearable. I found the following workaround somewhere (I’ve misplaced the reference):
$ sudo modprobe -r psmouse $ sudo modprobe psmouse
This works, but must repeated with each reboot. Looking forward to a more permanent fix.