If you don’t have a Magic Trackpad, you’re not going to enjoy Lion nearly as much as someone who owns one, though. Lion will probably quadruple Magic Trackpad sales. Here’s a tip: Get a Magic Trackpad and use it in addition to your (Magic) mouse. One on each side of the keyboard. Works wonders.
Maniacal Rage: Thoughts on Lion, Part I
I think this is one of the most sensible pieces of advice regarding the use of the Magic Trackpad in combination with Lion.