Though there is no indication that anything like this is in the works, one can easily imagine a streamlined Google OS on its own hard disk partition, separated from the entertainment, gaming, and media production environments. In addition to Google's signature services—a high-powered internet, media, and local disk search engine—it would likely consist of an office suite, a lean web browser, and various other applications and utilities. Consider the technology already at Google's disposal. Start with the world's best search engine with access to the largest body of searchable information and media. Add Gmail: a clean, javascript-based application, stored on a server, accessed via the internet, from which a user can not only compose, read, organize, and search their email, but also quickly access Google's search and other services. Now, look at Google News: a world of online news sources, which can be customized to an individual users preferences. Throw in Google's desktop search, the Picasa photo software, and Firefox (Mozilla and Google have significant overlap in their employed workforces) with live bookmarks, and cool research extensions such as dictionary and thesaurus lookup, linky, launchy, and the like. Extend all of this technology to typical desktop applications like office software, then combine them all into one interface and bundle the OS. Simple, powerful, and totally Google.
Let's take it one step further. Imagine that all of this software—like the Google search engine, Gmail, etc.—is stored on Google's notoriously well-backed-up servers and operates at relatively high speed with any internet connection, thanks to its simplicity and javascript code base. Supported by unobtrusive (sometimes even helpful) ads, and hosted on a distant server, this is free, convenient, and accessible from ANY computer, anywhere, anytime. Additionally, you have the world's best IT department working on your behalf to protect your software, its accessibility, and its security. No viruses, no worms, no corrupted disks.
Let's say they go even further: Google gives you, say, 1000GB on their servers, hosts all your data (with multiple levels of permissions), and provides everything mentioned above, and extends their video search (currently in beta) to provide access to a wealth of streaming audio (like iTunes radio) and video. All of it is free, all of it is easily accessible through a powerful, extensible web browser, and all of it simple and easy to use (it's still Google, remember). What are the implications of such a system? First, no more purchasing software (at least not the consumer grade applications hosted on the server); second, companies actually competing for your business (Google would surely be followed by the other major players); third, your work is finally mobile.
More: A Google OS by 2010?