Diego Doval's atomflow is more than just a Java based, queryable, persistent store for Atom. It's a nascent and promising attempt at applying the UNIX philosophy to syndication and aggregation. Write one excellent, but focused, tool and then rely on the surronding integration atmosphere to put it to use. In this example it would be UNIX style pipes to connect things together, and thus melt away monolithic blogging tools and aggregators.
Doval's partners in crime, Matt Webb and Ben Hammersley, make the case more eloquently than I can. Of course the overall surface ideas aren't that new, e.g. Kimbro Staken's Syncato covers much of the same ground. The difference is that atomflow seems like a microkernel to Syncato's monolithic kernel, to use an OS analogy. We'll see if it has legs.