After unsuccessful try on reddit.com, someone pointed me to a Python script that almost did what I wanted. Changed it a bit (works only with NetworkManager 0.9.x branch) and got: https://gist.github.com/1547663

Usage First parameter to script is VPN connection name in NetworkManager and second are comma separated names of networks that should be ignored (using VPN connection at home is useless). clone gist somewhere (eg. git clone git://gist.github.com/1547663.git /home/user/autovpn/)

add to /etc/rc.local: python /home/user/autovpn/autovpn.py "myvpn" 'Auto homenetwork,Auto worknetwork' > /var/log/autovpn.log&

reboot :-)