Comcast transit problems?

I'm being inundated with reports from Comcast customers in various markets about their inability to reach anything on AWS. For example, we have a few people in Atlanta that are all having this issue. What's more, they're having weird issues reaching things like Twitter or RingCentral (while other sites like Google and CNN work fine). (RingCentral's support department apparently knows about this and is telling their customers that use Comcast that they're aware of the issue but don't know what's going on at the present time.) Calls to the Comcast customer support just yield the "everything's fine, you're crazy" response from the staff. Can anyone from Comcast give me some help (or information) off list? -bt