More and more of our computing happens through applications and Web sites out in the network. It's in the "cloud" to use the current trendy lingo.
One consequence is that we're starting to look at our clients differently. That's because they're increasingly a sort of window into the cloud rather than devices that run a lot of application-specific code and store a lot of application-specific data locally. Clients can therefore be "thinner," which is to say loaded with less software and less tailored to the needs and wants of a given user. Resources and customization live out in the network instead.
Even with more conventional operating systems such as Windows, Linux, or OS X, running applications in the network reduces the time spent installing and upgrading applications on our proliferating collection of clients. Google's Chrome OS takes the concept to the next level and essentially reimagines the client OS for a cloud world.
However, the real world is messier and more complicated than "Just run everything in a browser." That's true today and will almost certainly be true to at least some degree next month and next year. Ultimately, this question of how thin clients can become as a practical matter is going to play a big role in how accepted certain models of computing will become.
To illustrate, consider a PC that is today mostly used to go online. There's more than just an OS and a basic browser involved.
There are plug-ins and extensions for the browser. There's probably an IM client; Meebo is a Web-based alternative but most people run a local client. If you use Twitter, there's a good chance you run an application like TweetDeck or Seesmic, which may in turn require Adobe's AIR runtime. Third-party media applications such as Apples iTunes are commonplace. Google Earth, Windows Live Writer...This list goes on--and will vary by user--of the applications and components that have to be installed and updated for even a rather bare-bones PC configuration.
And that's before we even broach device drivers or other software that may be required to connect a camera, a microphone, or some other peripheral.
My overarching point here is not that a thinner client model is uninteresting. I strongly believe that it is meant not to replace traditional fat clients but to augment them. Today, I have a notebook that is essentially used only to go online yet I still have all the administration associated with a full-blown PC.
However, the challenge for Google and others is to steer a course that creates an "Internet computer" that is legitimately better in that role than a full-fledged PC while retaining sufficient customization. Application stores may be part of the answer. HTML 5 will likely also help by making browsers more capable of running applications.
Whatever the specific technical solutions though, the answer will involve a lot of careful thought about balancing simplification and flexibility.