How can I disable the trackpad when my mouse is plugged in on Lion? For the last few hours my trackpad has been behaving terribly, jumping all over the place and sticking. I believe I remember there being an option to disable the trackpad when a mouse is plugged in in previous versions of OS X, but can't seem to find that option anymore.

Is such an option still available in Lion?
Thankfully, you can still disable the trackpad in OS X Lion.

Open System Preferences, click on Universal Access, select Mouse &amp; Trackpad and click on Trackpad Options... at the bottom. Tick the checkbox "Ignore built-in trackpad when mouse or wireless trackpad is present".