I can't tell you how many countless times I've setup Ubuntu VMs for development, but I've only for the last couple of years done so on a linux host. This whole time I've been setting up /etc/hosts (frequently) because I couldn't find a great way to get hostnames working between the two. Well, the following snippet will get you everything you need to get the two talking over Bonjour:
Simple enough right? You can test this out by typing trying:
Where guest is the hostname for your guest machine.