Go to Library/Filter by Metadata/Enable Metadata Filter.
The Metadata Filter pops up and you can see all the lenses and how many shots with each.
Select a lens and you see all the images taken with that lens.
I was going to complain that the above only gives you the lens and not the actual focal length within a zoom, but I did some digging as I wrote and found that once you've clicked on the Metadata tab look to the right and you'll see
No Filter in a small window. Click on that drop-down and choose
Camera Info and it will show you the breakdown by focal length and whether or not the flash fired. Choose
Exposure Info and it will show you the breakdown by ISO, Aperture and Shutter Speed.
Lots of good stuff in there!! It's going to make life a LOT easier next time I need to find something like ISO 6400 images across various cameras so I can compare them.
While I was poking around I found this blog...
Rummaging Around in the Lightroom Database - Photo Tips @ Earthbound Light
...and being a SQL nerd I am intrigued by the idea that I might be able to write queries against the LR catalog (or more specifically, a copy of it - I don't want to screw it up). Need to dig into this when I have the time.