I know many of you are like me and hated the "lag" when "right clicking" in Lion so you probably turned double tap to zoom OFF which fixes the issue. I have discovered that even if this feature is off, if you spread your two fingers apart as if you had just zoomed in, double tap with your fingers in that position and you still get double tap to zoom. Pretty neat! Sorry if that's confusing, it's hard to explain. Try taking your index and ring finger and placing them at the bottom left and top right of the touchpad and double tap. Voilà!