I posted those stats 'elsewhere' and went and found them.

As at the 14th June when first posted:

On the buying board there are currently 34 pages of threads, and once you get half way down page 5 the threads have been idle for more than 12 months.

On the selling board there are currently 66 pages of threads, and once you get half way down page 9 the threads have been, you guessed it, idle for the last 12 months.

Mods already have the ability to lock threads manually, so all they need is a memo from the eBay Community Manager (that would be you michelleoz) to start locking threads.