> With the current CVS HEAD:
 >
 > emacs -Q -nw
 > M-: (setq pop-up-frames t) RET
 > C-h f ding RET
 >
 > The *Help* buffer does not appear at this point, a new frame is created,
 > but the current frame does not show the help buffer.

I'm aware of this problem.  Does the attached patch fix it?

 > with emacs-22.2 the *Help* buffer is displayed.

Not here on Windows.  And I wonder how this could work on your system.
FWIW, the underlying logic did not change.

Does `pop-to-buffer' for some arbitrary, non-visible buffer work with
-nw?  What happens with `display-buffer'?

martin