In the previous Curious Case I described an issue Jonathan had at a client with very long IAM chains, and the circumstances leading to it.
The question was how to prove that some allocation units had IAM chain lengths way out of proportion to the amount of data in the allocation unit, without tediously walking through each IAM chain, starting with the first IAM page (whose ID is always stored in sys.allocation_units internal table).
The answer was to do exactly that, but remove the tedium by writing some nifty code to do it, making use of the sys.dm_db_page_info DMF that