hmm, looks like an uncomplete install..
here's what i get on my system:
CODE
Last login: Sun Aug 19 10:46:19 on ttyp1
Welcome to Darwin!
macpro:~ chris$ which shake
/usr/bin/shake
macpro:~ chris$ ls -la /usr/bin/shake*
-rwxr-xr-x 1 root wheel 292 Jun 7 2006 /usr/bin/shake
so there should be a shake executable in /usr/bin/
as it's only 292 bytes i suspect this is just an link to the shake executable in shake.app, you could try to ln it from there to..
CODE
macpro:~ chris$ ls -al /Applications/Shake/shake.app/Contents/MacOS/shake*
-rwxrwxr-x 1 root admin 415828 Jun 7 2006 /Applications/Shake/shake.app/Contents/MacOS/shake
if in doubt i'd rather reinstall.
hope that helps
++ chris