There were lots of announcements made this week at Google’s I/O developer conference in San Francisco, but the thing that stood out most for me was the unveiling of the Chromebook.

Running on Chrome OS, it represents a computing paradigm shift in having the entire user experience reside within the browser. This sheds big heavy operating systems and software (read: Windows), in favor of a lighter experience that includes an eight-hour battery and eight-second start-up time.

The disadvantage is a lack of robust word processing (Microsoft), or creative/graphics software (Apple). But the thought is that more and more of our computing activity is happening within the browser. Things like HTML5 improve functionality, while 3G and Wi-Fi saturation enable it.

And Google fills these application gaps with Web-based products like Google Docs and apps from the Chrome Web Store. And of course this all comes back to driving more Web use, which translates to more search — Google’s core revenue source.

Stepping back, all these factors are in line with the move toward the “post PC” era. That mostly involves smartphones and tablets, but also importantly includes cloud-based computing and a move away from big heavy devices and operating systems. The Chromebook is very much a part of that.

The question is whether this move toward a Web-based world will migrate to mobile. This is at the heart of the “apps vs. mobile Web” debate, where many argue that all these factors empowering the PC browser will signal the same shift toward the mobile browser (vs. native apps).

As for the Chromebook, there are models launching next month from Samsung and Acer. They’ll be $28/month for the business edition, and $20/month for education. Support and security are key elements, meant to appeal to corporate IT departments (another shot at Redmond).

As a sidenote, the ad copy for the Chromebook is a good example of ad agency tunnel vision, or perhaps too many cooks. In what seems like an effort to get too technical, there appears to be a missed opportunity to push the slogan/tagline “Nothing but Net.” Instead, we end up with this: