Using my Mac as the host machine, I followed all the instructions on the Drupal Vagrant project page at http://drupal.org/project/vagrant to get a Vagrant automated Virtual Box Ubuntu lucid32 Virtual Machine up and running with a Drupal 7 stack.
However when I try to use my browser to connect to the server, using the URL addresses stated in the instructions on the project page, it doesn't work.
(The same steps work when using Windows 7 as the host machine.)
The error message, for example, in Chrome is: "Oops! Google Chrome could not connect to dev-site.vbox.local"
The Vagrant VM seems to be running OK and I can connect to it using vagrant ssh.
I also flushed the DNS cache using dscacheutil -flushcache
Mac OS 10.7.5. 4GB RAM. MacBookPro 2010.