[Typo3] page-tree architecture

[Nagita Karunaratne]

Does anybody know if there are other CMS (both open-source and
commercial) that use the page-tree concept?

Is this a very common architecture or are there any others? Can you
give examples of other architectures?

I have seen some CMS that do the editing on the front end and the
back-end is used mainly for administration.

Also can anyone with experience/knowledge of  any commercial systems
(simple or complex) shed some light onto the different ways that these
systems use to organize their users interface.

Thank you,
Nagita