Thanks.  This ling seems close to addressing the question.  I was a little
unsure after reading it whether a converter tube is needed, but I guess not.
The WCON-7 must have male 55mm threads on the back, meaning it would screw
right into the FZ30 lens.

The shadow with the built-in flash would be sort of expected.  If you wanted
to photograph a banquet e.g. you'd need an external flash.  Taking pictures
of architecture or landscapes outdoors would not seem to be a problem.  I
was concerned about vignetting and focus.  I don't know how critical the
distance is between the front of the Elmarit glass and the back of the
Olympus glass.  To be dead sure, though, I'd like to see the results with an
actual FZ30.

Of course, putting an Olympus converter in front of a Leica lens is a bit
hokey.  But then, the whole area of converters (Vorsatzlinsen) is a bit
hokey.  I want it just for occasional use.  If I were really going to need
this angle a lot, of course I'd want a camera with interchangable lenses.

--Nemo