Currently the reverse pool buildlets say at http://farmer.golang.org/ :

darwin-amd64-10_10: 2/4
darwin-arm-a5ios: 1/1
darwin-arm64-a7ios: 1/1

But that's a little confusing, because you can't tell the difference between an iPhone building, vs an OS X amd64 build running.

I think instead of just "N/M" it should be "N+O/M":

(builds-of-this-type)+(builds-of-other-type-on-same-hardware)/(hardware-count)

Aside: it should also be doing darwin-386-10_10.

/cc @adg