We've not made much noise about it but something that Paolo and I have been doing is working within the framework of RSS2.0 to deliver what we see as useful functionality. ENT 1.0 is one of those things, another is SGUID.
SGUID allows an aggregator to unambiguously identify the post that an aggregated post is referring to. By default RSS2.0 only allows you to identify the feed. The upshot of SGUID is that aggregators could implement simple threading and allow readers to browse back through a series of postings with ease. Whenever I repost an item from my aggregator now, my post get's the appropriate SGUID.
SGUID is simple. We're hoping it is useful as well. [Curiouser and curiouser!]