In the release version of Mac OS X 10.7, there is a bug that prevents secondary click working with two-finger click on the Macbook Pro 4,1. The only way to right-click is using Control+click.
To enable right-click using two-finger click, run the following in Terminal:
defaults -currentHost write -g com.apple.trackpad.enableSecondaryClick -bool YES
After doing this log-out and log-in again.
[crarko adds: I don't have the hardware to try this on, but if people with the mentioned MacBook Pro have (or don't have) this problem please mention it in the comments.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20110721194321910