The reason is it's an idea that wasn't ready for anyone to think of before. Two things have changed in just the past couple of months in the way that people think about mashups and the Web, and Live Clipboard captures both of them in a really crisp and yet innovative way.
(Oh, and the other reason is that Ray Ozzie, unlike most of us, actually has a team of people down the corridor whose sole job is to develop concepts for him. Run by his brother Jack. Now wouldn't that be handy, every time you thought to yourself, 'I wonder if ...', you could walk down the corridor and have your brother get a team of people onto it. That would be so cool.)
So what's changed to make the web clipboard an idea whose time has come? The way we think about two things:
Structured web data. After being the sole preserve of a team of slightly wild-eyed geeks at W3C — plus Jon Udell, who is just one of those guys who gets things two years before everyone else — suddenly structured web data is something that ordinary people see the point of doing. Mainly because of edgeio, which in a blinding flash just makes it obvious why it's worth structuring the data you publish online (why? so that edgeio can pick it up and promote it for you). Of course edgeio wouldn't make sense if the ground hadn't been prepared by XHTML and RSS and the Structured Blogging people (and the sneaking feeling that if Tim Berners-Lee says it's a good thing the Semantic Web probably does have a purpose after all, even if no one can make head or tail of it). After all that softening up, along comes Ray Ozzie with his Live Clipboard demos, and we suddenly realize that the point of structured web data is to save us retyping and reformatting the same damn information over and over again every time we fill in a form or copy some data on a Web site, and of course we all want to sign up.
Self-service integration. Bit by bit, integration (or, more properly, loose coupling) has been democratized. First came APIs and open services. Then came AJAX and mashups. But these still required technical skills to assemble together. Some of us have always wanted to go further and deliver those capabilities directly to the end user (Adam Bosworth and Brian Behlendorf, to name just two). So along came Ray Ozzie, musing on all this and asking the question, "What would it take to enable users themselves to wire-the-web?" Now that everyone seems to be doing mashups, the question no longer seems absurd. And that's why the answer suddenly seems so obvious.