Last week, Microsoft shook up the RSS community with its announcement of "bi-directional RSS," introducing a new specification that takes RSS from a uni-directional, publish-only model to a bi-directional model. You can check out the details here: http://msdn.microsoft.com/xml/rss/ssefaq/.
After a quick review, I think "bi-directional" is purely in a technical sense. Although it is a huge idea, it won't have a very big impact on marketers. The ability to have a two-way dialogue doesn't appear, at first glance, to have any application to customer/prospect dialogues. My read is that the primary purpose of this new specification is to make an open (and hopefully universal) language for synchronizing different data sets. For example, it could be used to synchronize your calendar with your spouse's calendar, even if the two of you use different systems to track your appointments.
RSS continues to build as a universal communications platform. Regardless of whether this latest specification has an immediate impact on marketing, the fact that RSS continues to escalate in awareness and application means that it is becoming an ever-present part of our computing future.