So. This one is pretty much only for HUGE fans of the Q system.
The next cheapest I can find is £350, and Jessops has these for £429 (!!!).
In itself it seems pretty pricey - as much as the Q7 - but from what I've heard, it's a good lens.
On the Q and Q10 this gives an equivalent view of 21.3–33mm and on the Q7 it gives you 17.5-27mm
There's a fun review I found on youtube here- https://www.youtube.com/watch?v=PexGKkZ5dKU
and there are some nice example images in this forum thread - http://www.clubsnap.com/forums/showthread.php?t=1351456