On SuSE 9.2 we have noticed that sudo didnt seem to work out of the box. Have tracked this to SuSE changing a default from the way it is shipped in the sudo package, from the man sudoers(5) man page:
targetpw If set, sudo will prompt for the password the user specified by the -u flag (defaults to root) instead of the password of the invoking user. This flag is off by default.
If you comment out the following line sudo will ask for the password of the current user NOT the user they are trying to run the command as: