[Spivak]

I think the issue depends on whether a service is acting as a principal or an agent. If a user signs up for your service and says "I would like to subscribe to Mox News" and you pull data on behalf of your user then I see no issue.

But in the same way you as an individual couldn't republish those copyrighted works, your aggregation service where you choose from sources and publish your links and summaries wouldn't be okay.