Finally got my N7 setup with multiuser goodness from JB. However my son in attack of curiosity locked himself out with security pattern. Well… I didn’t 😉 Thanks to always helpful XDA: [GUIDE][HOW-TO]Crack android pattern lock! solution was really quite simple:

# find / -name gesture.key 
# mv /data/system/users/11/gesture.key /data/system/users/11/gesture.key.bak