I just submitted a change to this entry so that it would become the official listing for sudo, and it has been approved.
Now, read this important article about a vulnerability in the out of date versions of sudo that are included with OS X:
Until Apple provides a security update, the easiest way to fix this is to install a copy of sudo using the links in this entry (or via a package manager such as MacPorts), and then overwrite the Apple included sudo binary so that it can't be invoked. If you use one of the package installers, the sudo binary will be placed in /usr/local/bin. After installing, to patch your system, enter at a terminal prompt:
/usr/local/bin/sudo chmod u+w /usr/bin/sudo
/usr/local/bin/sudo cp -p /usr/local/bin/sudo /usr/bin
/usr/local/bin/sudo chmod a-w,go-r /usr/bin/sudo
If you've installed sudo via MacPorts, then the commands would be:
/opt/local/bin/sudo chmod u+w /usr/bin/sudo
/opt/local/bin/sudo cp -p /opt/local/bin/sudo /usr/bin
/opt/local/bin/sudo chmod a-w,go-r /usr/bin/sudo
As I said, Apple will eventually provide an updated sudo binary, but to fix it right now, the system sudo needs to be replaced.