As I said in my Shittng Point post about blogging, an indicator of what's next is to look not where people are going now, but where they've have been disappearing to all along. Second Life as an OS is a Huge Concept; it's also right on.
And not just a computing OS -- also a social OS, a business OS, a religions OS, an education OS.
You think we've been talking about social software? Oh baby. We're talking a social architecture.
Essential reading on why at Scoble's (plus comments) here.