Aggregation networks that focus on a individual users experience across mutliple channels rather then a single channel will be the driving force for the next wave of big startups IMO (and providing they can get the data cleanly).

ALTO confirms this, Its not just a new paradigm for email UX but communication UX. HootSuite and others have attempted similar by focusing on a few networks or channels and they have shown that people want a service where then can manage their online profile and communication from a single system. Attach email and file management capabilities and its a one stop shop.

btw: I would also add this is where Google has failed to capitalise in the marketplace. Users don't want another social network, The want control of everything from a single point.

Is this one of Paul Graham's Frighteningly ambitious startup ideas in the making? http://paulgraham.com/ambitious.html

Is AOL's current position that of an incumbent or a disruptor?

First MySpace and now AOL. There's some great design where you least expect it. :)