Secondary click in Lion with two fingers OR bottom-right corner click
Run the following six commands, by pasting them into Terminal.app. You can paste all six lines all at once. (the last two lines aren't required on older versions of OS X, but there's no harm including them) Remember to press the return key:

defaults write com.apple.driver.AppleBluetoothMultitouch.trackpad TrackpadCornerSecondaryClick -int 2

defaults write com.apple.driver.AppleBluetoothMultitouch.trackpad TrackpadRightClick -bool true

defaults -currentHost write NSGlobalDomain com.apple.trackpad.trackpadCornerClickBehavior -int 1

defaults -currentHost write NSGlobalDomain com.apple.trackpad.enableSecondaryClick -bool true

defaults write com.apple.AppleMultitouchTrackpad TrackpadCornerSecondaryClick -int 2

defaults write com.apple.AppleMultitouchTrackpad TrackpadRightClick -bool true


Important: now reboot your Mac. 

When you log back in, you will be able to right-click both with a two-finger tap, and by clicking in the bottom right-hand corner.

Hope this helps.