sudo: must be setuid root (Mac OS X)

I ran

$ sudo chown -R $USER /usr/bin 

and now when I try to run programs under the /usr/bin path as sudo I get

sudo:must be setuid root

What should I do if I would like to revert the chown?

Run Disk Utility, select your boot volume, and use "Repair Permissions". Since the files in /usr/bin (including sudo) were installed as part of the OS, it knows what their ownership and permissions should be, and it'll set them back properly.

xattr /usr/bin
com.apple.FinderInfo
com.apple.rootless

xattr -d <extended_attribute> /usr/bin

that will remove the attribute, so you can do the commands, then make sure you re-enable the attribute when you are finished:

xattr -w <extended_attribute> /usr/bin

that will re-enable the attribute.

Ozz