You are allowed to:

- Alter the program visually or change its "theme" if you wish to do so.

- You may remove the "pyForum.org" logo in the application header and replace it with your own logo (the new logo does not necessarily has to have a reference to "pyForum" ro "web2py").
You may not:

- alter the "footer", the "Powered by web2py" and the pyForum text and version information must remain at the footer at all times.
Finally..Since RC2, this application has been released under the GPLv3That's it, easy enough I think right? - A word of caution, I'd advise against radically modify the application (please read LICENSE also!!!), since I will be releasing many updates in the time to come, unless you are a great merger, you'd have difficulties in keeping up with the application update, just a suggestion.
-- sb