One could argue that a template variable of "user_some_funky_permission"
should be created by the application.   But then why should the
application programmer create the cross-product of every template
variable; it is up to the template designer to decide when the
some_funky_menu gets displayed.

I agree with what Mathew says (especially about commonly used filters) except
for this quoted bit.  I seriously disagree with the idea that designers should
be doing bitwise operations.  I think it is one step too far down the road of
integrating code and presentation.  That being said - I would never use it so
it's inclusion/exclusion does not concern me.  I do believe it goes against the
spirit of H::T though - maybe it should be in a plug-in.
I agree - in fact it already is a plugin => this functionality would only be available in H::T::E.