Dave Winer has announced OPML 2.0 (in public review status currently). OPML stands for Outline Processor Markup Language. In semi-laymens terms, OMPL is a common XML data format for outlines and subscription lists - just as RSS is a common data format for content syndication.
So why is OPML significant? Its main claim to fame so far is as a way to import and export subscription lists between feed readers and aggregators. But other uses, such as Reading Lists and as a mechanism for filtering your information load, may be its real future. For example, all the recent talk about personalized 'memetrackers' (or news trackers as Gabe Rivera from memeorandum would prefer we call them) hinges on OPML.
The theory is that people can personalize their news filtering by uploading their OPML files - aka subscription lists - to the likes of TailRank, Findory and Megite. It's still a work in progress and some developers think it's too hard a problem to solve right now. But I see this as an indication of how big a part OPML has to play in the future of media filtering and personalization. I certainly think it's a key technology, just as RSS is.
As the man himself, Dave Winer, wrote:
"OPML 2.0 is a milestone, much like RSS 2.0 was in the summer of 2002. We now know how OPML is being used, and where the problems are, and I think are ready to produce a frozen and extensible format and spec."
RSS 2.0 is the dominant syndication technology currently and so perhaps that augers well for OPML 2.0.
p.s. what's the best and easiest OPML editor out there currently?