Well, I'm by no means a heavy email user. I get maybe one email a day that I care about... and that's on a good day. I don't bother with notifications and aggregations and all that mess (or social networking for that matter). But in any event, the advantage email has is that your inbox is an aggregator and that email is ubiquitous. Email is already preconfigured, preprogrammed to work with anyone. Sure, you may be able to make a nicer way to get notifications and updates from certain sites (though I still can't for the life of me figure out why you'd want to), but will it work with every single site in existence and with every single person in existence and with every single other technology in existence? No? Ok, I'll stick with email then.