Jason Kottke opines that since the major usage of RSS and Atom is presentation and browsing in tools like FeedDemon, the term syndication is becoming less appropriate. I agree, but I'm not at a loss for what the right next term is: aggregation.
The unifying element amongst the current crop of microcontent browsers is that they collect from multiple sources. The only other unifying concept is the push, automated update, mechanisms they all have.