Dennis,
I'm not really looking at normal exchanges where some participants offer
transit or partial transit. I'm looking at exchange fabrics specifically set
up for the purpose of selling services, be they transit, partial transit, or
paid peering.
Most of these exchanges have web based administration, route servers, flow
accounting, or some other combination of services. A good example is
Equinix's Equinix Direct. Equinix maintains a series of exchange fabrics
that are primarily for settlement free peering, but also has exchange
fabrics set up, specifically, for buyers and sellers of services.
Telehouse in NYC was doing something like this, as well. I'm not sure how
far it has progressed.
Thanks,
Dan