Okay..this is crazy...but...
is there...or can there be an adapter to put the 20x Canon zoom lens (that comes with the Canon XL-H1 Camcorder)....on a Canon 7D ?

I've not had any experience with that lens or with the XL mount, but my guess is that the image circle would be way too small. You would get severe vignetting. Some things just weren't made to go together.

John's right -- even if you could find a way to mount that lens, the image circle it creates wouldn't begin to fill the frame on the 7D. You'd be looking at a mostly black screen with a little round image in the middle.

Well...that's pretty much what I figured....since the XL has a 1/3" chips....the imaging are would be much smaller than the 7D....BUT...didn't know if someone crazy had built some sort of optic adapter to fix that.

Oh well.....but the 7 D would look pretty cool with that lens on it wouldn't it ??!?!?!

Get the 24-70 L lens. It's about the same size.

You also need electronics to wake up the iris ;et alone change it. When the XL lenses lose power when the camera is turned off the iris fully closes and won't open until it's told to by the camera being turned on.
Steve