sudo offers updated binaries for OS X 10.5 and up so you don't have to wait for Apple: http://www.sudo.ws/sudo/download.html#binary

If you don't trust the binaries, I found it easy to update the vulnerable sudo v1.7.0 on my OS X 10.6 machine by building from source and overwriting the one supplied by Apple:

0) Backup /usr/bin/sudo (temporarily; you'll want to delete the old sudo after verifying the new one works), and backup /etc/sudoers just to be safe

1) Download the source for sudo v1.7.10p7 linked on sudo's homepage: http://www.sudo.ws

2) Untar, ungzip, go to resulting source directory

3) Run configure, telling it to overwrite the vulnerable sudo

    configure --prefix=/usr/bin

4) Compile

    make

5) Install

    sudo make install

6) Delete the old sudo you backed up in (0)

See also the sudo installation notes here: http://www.sudo.ws/sudo/install.html