Simple steps for getting new IP address via DHCP on Ubuntu (tested on Ubuntu 11.10, running under vmware with bridged network)
# Release existing
sudo dhclient -r
# Get new
sudo dhclient
# Restart networking
sudo /etc/init.d/networking stop
sudo /etc/init.d/networking start
sudo dhclient -r
# Get new
sudo dhclient
# Restart networking
sudo /etc/init.d/networking stop
sudo /etc/init.d/networking start
