the cable lengths quoted are pretty peculiar - no in-rack cable needs to be 5M - 1.5-2.5 would be preferred to minimize the excess. and 30M to an upper-level switch is also a bit extreme, since it's easy to arrange ~50 racks within a 10-12M diameter (even for a spread-out air-cooled cluster). I wonder whether they said meters but were thinking feet...
that anecdote from the patch-panel maker is pretty sad. they seem to be thinking of traditional IT, not clusters. a cluster will not normally use any patch panels: nodes connect directly to the leaf/TOR switch, and they connect directly to spine switches. it would be sad if archaic cable-length concerns quashed this effort.
I wonder how much the PHY is keeping switches from getting reasonable-priced. 10G won't really take off until its per-port switch+cable+nic price is very close to 1G (let's say, around $100.)
Great article Rick. One point that was not captured is that it takes 75% to pass a technical motion in the IEEE Study Groups. While there was support among a broad range of participants, a popular proposal can lose with a 74% approval.