This is a _very_ interesting question in light of what I just posted...
the CIX has the (odd, these days) feature that peering is mandatory for all,
and so large providers don't get to choose whether or not they want to
haul traffic across the country for these people.
There is no such thing as mandatory peering. Several folks on the SMDS cloud
purposely do not peer with certain other folks on the same cloud. Everybody
peers with the CIX routers, though, and with third-party BGP routes that means
most traffic is just point to point. (The SMDS access lists are not perfect,
so there are some in-and-out cases for various endpoint pairs.)
ps. We'd already be at CIX if certain providers had more than a T1's worth
of bandwidth available out of there, specifically to take advantage of the
"mandatory peering" situation. Heavily-loaded small pipes to interesting
places aren't useful, though.
The link you're alluding to is probably SprintLink's. It runs at or near
capacity for most of every day, and while that's usually an indicator that
a larger pipe is called for, it's also an indicator that the link is of use
to at least some folks.