I have not done so on Ubuntu, but I did run our original wireless implementation on a CentOS box running chillispot/freeradius/dd-wrt. It wasn't horribly difficult to setup and management was fairly reasonable. While it wasn't tied to our AD infrastructure, it was fairly simple to add/manage users and guests could be created with an account that automatically timed out.
I have not done so on Ubuntu, but I did run our original wireless implementation on a CentOS box running chillispot/freeradius/dd-wrt. It wasn't horribly difficult to setup and management was fairly reasonable. While it wasn't tied to our AD infrastructure, it was fairly simple to add/manage users and guests could be created with an account that automatically timed out.