You can grab what I quickly assembled for siggraph:
(with help from Ianwill

http://www.blender.org/bf/demos.zip (2.5 MB)
Just drag one of the .blend files on top of a 2.34 Blender executable (works with osx, windows, linux). Or start blender 2.34 and load a file.
You can exit looping by pressing ESC (sometimes twice).
In the current API, only the Play() call returns an event to denote ESC is pressed, so that's still a bit awkward.
(For useful demo looping having an ESC is crucial.)
Nevertheless, it's a very interesting method to explore two things;
- an automatic testing environment
- make a demo CD to hand out on tradeshows and send to stores
Especially the latter I like to do work on; it should be possible to make a demo cdrom that shows all kinds of Blender features in a loop, and which doesnt require any installation at all (e.g. runs from CDROM completely).
I would need more experienced python scripters for it however, so hopefully people like to pick this up and create their own 'demos'

The current python API allows to do *very* interesting things!