Bear with me, as usual I've not thought this through thoroughly (but I will quote myself a few times :)
There's been a flurry of commentary recently about the threat to the "Common Web" from things like Facebook, Google+ (e.g. see posts from John Battelle, Robert Scoble). There's also some fragmentation of the Web going on around "Apps" in Apple's mobile device sense. The main antidote proposed for this kind of thing in recent years has generally been to use non-silo'd, non-walled garden services.
But I'd argue that it's a more systematic problem, that switching service won't necessarily solve. Remember we already have an open distributed social network in the form of the blogosphere. Where is the advantage in Facebook, G+?
More generally, so much current technology is geared towards that one page you have open in the browser right now, it's like looking through a narrow pipe at the Web. Web Intents and the Firefox work on push are likely to alleviate the symptoms somewhat, but still the underlying problem isn't being directly addressed. The browser has become a bottleneck.
One approach to counter the walled gardens and silos (and associated issues like privacy) is to host all your own stuff (check Steve Pemberton's Why you should have a web site for starters). Depending on your ISP setup, it may be possible to serve direct to the Web from a home host. So why not manage all your data locally? That makes it easier to manage how much control of your own stuff that's handed over to other services.
Ok, you might argue that's something we're (more or less) all already doing. Maybe. But where is the Web? I suspect most people consider it conceptually (as I usually do) as out there. Why should it be here too? Ok again, there's been loads of work done over the years on P2P systems. We've seen things like Microsoft's Personal Web Server. But note: "PWS was useful in developing web applications on the localhost before deploying to a production web server.". The approach here, and with many other comparable systems (certain blog editing software, for example) is that the local material is offline and copied to a remote server (via ftp or whatever) to make it live.
I think the time might be right to look again, and consider making the localhost the live host. Where the wiring doesn't support direct serving, what's needed is a transparent, real-time connection to a remote endpoint to simulate a local/global connection to the internet. Not trivial, but then again there aren't any hurdles that haven't been leaped in other contexts. There are several ways this could be achieved, maybe the most straightforward based on standards would be using an XMPP-based bridge between the local and remote machines, with a fair bit of caching on the remote machine for performance. Should be commoditizable.
Of course this would demand a full stack locally - if you were using, say, a MySQL store behind your CMS, that'd need to be running locally, along with all the interpreters for PHP etc, together with whatever message dispatch switching you'd ordinarily use on the remote host. But I think it would be advantageous to manage information locally using Web-oriented technologies - in particular linked data. Let the Web in.
Why am I suggesting this kind of a setup, just as everything appears to be moving to the Cloud? Well this isn't anti-Cloud, quite the opposite. It's bringing the Cloud right back home, to encourage greater participation. Avoid the bottleneck of the browser (and a handful of lower-level protocols like ssh) to connect with the Web, open the floodgates with other local agents interacting with your own data and through the HTTP bridge, and allow as many parallel channels as you wnat, in addition to the browser. It is the 21st century, after all.
PS. within seconds of me posting the link to G+, Melvin Carvalho responded:
Already doing it. Dyndns and apache let you run a pretty decent web server. Then I have a linked data space on my desktop https://github.com/linkeddata/data.fm . I also have a little script which links my personal data space to my online presence when I'm logged on. I wonder why in 2012 more people dont run a personal server.