The CDN Ecosystem diagram has been updated, and now includes the only two Telco CDNs in the US, EdgeCast Verizon and Level 3. These two are different from all other CDNs in that they are part of a Carrier. EdgeCast Verizon is the only last mile CDN provider in the US. Essentially, that means they can deliver content from the point of creation to consumption over the last mile, over wireline and wireless, in many parts of the US. However, this is only possible if Verizon cross connects their Tier 1 bandwidth into the EdgeCast POPs, which I would assume would be the case.
Level 3 is not a last mile CDN, but a CDN that owns its global fiber network. The difference between Level 3, and other CDNs is that the other CDNs buy bandwidth from multiple ISPs at each POP. As such, the CDNs have control on what ISPs delivers content. Limelight and EdgeCast might use a combination Verizon, AT&T, Level 3, NTT, Telstra, PCC, and DT at their POPs. Having control is important because the CDN can choose a specific ISP for a specific region. DT offers excellent performance in Europe, Telstra in Australia, and PCC in APAC. Using an ISP in a region where they have minimal presence will impact content delivery performance.