While trying to use Xubuntu 14.10 Utopic Unicorn, the trackpad isn't supported by default. I followed the lead of a reddit thread which suggested upgrading to a newer kernel. Ubuntu just happens to provide the latest kernels, you just have to know where to find them. I cropped the recommended URL in the reddit thread to just http://kernel.ubuntu.com/~kernel-ppa/mainline/, which displays all the latest deb releases of kernels and then names them for the release using the codename.
When I wrote this blog post, the latest 3.17 kernels for 14.10 were at: