We have developed a web application running on Linux that is quite popular. We now wish to release it as an appliance so customers can run it internally on their own networks. 
We are unsure of the best approach. We are flexible on areas such as: the Linux distro, whether it's a hardware or software only appliance. Does anyone have any advice on the best way to go about this? Links to any good resources on the subject? Questions we should be asking ourselves? Legal considerations for a commercial app? Security considerations?
UPDATE:
It's a Python based web application. We would like the user to be able to do everything via a web interface. No command line stuff etc.
It depends on what langauge/tecnology application is written.
If it is java, release war file + tomcat/jboss.
If it is python, release eggs.
If it is php... not sure, probably just .tar.bz2.
Linux distro or virtual image mught be advantage, but I dislike using them, because they are usually does not fits to my infra (why do I have to install some custom debian-based distro to my rhel-only infrastructure?).
Considerations for moving our web app to an appliance