I've actually signed up for Cogent's service. (Score 1)

Cogent has a bunch of positives to their service. First, they own the network between the sites that they plan on lighting up. The fiber has been purchased; the backbone routers are in place, as of Oct 15. The FIRST building to get lit is 440 S LaSalle, in Chicago, the Chicago Board of Options Exchange (actually the office tower behind it). This is scheduled to happen November 1st, and if so then I will be getting a very fun phone call that day, asking if I still wish to go online with them.
However, what the majority of you are missing is this - if I buy links in other buildings across the nation, I now have an incredibly cheap WAN, at 100 mbs. Cisco all throughout, so VPN becomes that much easier. A dedicated point to point from Chicago to San Fran is easily 1-2k a month, even from a discount carrier such as Qwest. Also, Cogent explicitly states in its literature that they don't plan on providing access for everyone - just for the companies in the buildings they light up. That boils down to only major metros, and buildings where fiber already has been run, so as to reduce fees for Cogent.
I'm sold on the service. I've alreayd signed up 4 buildings. Here's to hoping they pull it off.

-Hello Slashdot, I'm a first time poster.