I've been thinking about this very idea recently and then came across this article from @jeremiah. I was mostly coming at it from a product and user experience perspective. It seemed that a some of the 3rd party services based on Twitter (and Twitter too) have been coming full circle and deploying email-like strategies for both functionality (routing, groups, etc.) as well as the presentation layer (check out seesmic's list view on the web). Think also about how important email is to Twitter and facebook's user experience: where would they be without "now following" or "comment" emails? In the meantime, while those guys duke it out, Google has been infusing the social piece into their apps, and they've been doing it for some time now. With the recent social networking enhancements to GReader (in addition to GShare) they seem to be at it in ernest. Given the reliance on emails to bridge relationships between user/service and user/user, plus the adoption of gmail (among other G built pl