I wrote yesterday that there will AT&T announced that they are the latest. Gloating aside, this proves that the market is still being shaped and that it won't necessarily be the domain of BigCo tech companies.and today
In reality it makes perfect sense that major telcos would become Cloud providers. They own the bandwidth, network and have data centers all over the world.
AT&T and Sprint have long offered hosting services including data center space, managed servers and services and of course network connectivity. Data centers are expensive and require ongoing maintenance. The expense of such build-outs will not be easily dealt with by an upstart provider.
This also suggests that the Cloud definition will be stretched further and that there will be more mutations of public and private Clouds depending on who the customer is.