All of these are hacks. Interesting and useful, but hacks. None of these will be around in ten years. It's not the kind of future-inspiring innovation the author was referring to.
Web applications don't seem trivial -- they are trivial. Scaling them means being creative, but don't confuse that with true innovation.
Don't be so quick to dismiss 'hacks'. Important innovations often start out in unrelated fields, or build on discoveries or solutions attempted in unrelated fields. We don't have to look too far for evidence of this: the Internet, the laser, and the computer were all important inventions that changed the world in ways its creators never intended them for.
I'd argue that innovation happens in widespread tinkering. So it could be true that most of the tinkering today happens to be on webapps. But it's presumptuous to assume that none of these attempts would result in innovations of significant worth to humanity.
I say this without irony: I think that Facebook changes everything. If Facebook is not around in 10 years, then at least one social networking site will be. People want to be able to easily communicate online with the people they know in a global way. Facebook is becoming the global human database.
You're right that a global database, partially about us and our relationships (including a social network), is the future. Many are working on it, including me. And Facebook has some seed data for that, but that's the extent of it.
We'll remember Facebook in ten years the way we remember MySpace now: We don't. Facebook changes nothing.
I can see the changes Facebook has made in how people communicate right now. This is not a prediction, I can observe it. I know people who no longer use email and exclusively use Facebook for online communication. They share vacation photos with their family and friend sthrough Facebook. They announce life-changing events through Facebook. I, personally, have maintained communication with people that normally I would have just stopped talking to. These are not hypotheticals. These are real, actual changes in how I and others communicate. Facebook has an order of magnitude more users than the previous attempts - Friendster and MySpace - and is able to have much more impact than them because of it.
If you're working in the same space as Facebook, you're not doing yourself any favors by denying its impact. One, it harms your perspective, and two, it harms your credibility.
Web applications don't seem trivial -- they are trivial. Scaling them means being creative, but don't confuse that with true innovation.