This is a pretty common thing if you want to get absolute separation for applications within a single (large) vm and is used extensively in the PaaS world. Have a look at cloudfoundry (look on github). This is how it manages containers for each application. Heroku, dotCloud and others seems to follow similar approaches.

Long answer short, a lxc container would look like a self-contained vm to everything outside and from within (except for the controlling vm). You can go with the existing model but I would recommend using one container per application/service. Also have a look at: https://github.com/dotcloud/docker‎