Please follow the links and read the original announcement. It's a general-purpose OS only in the amount in which web applications can fulfill all your needs, as it will be basically a Chrome browser acting as a shell running over a Linux kernel, probably leveraging remote storage and the such.
It can basically replace Windows and its Office suit for some users who can work with Goggle's web-based word processor, spreadsheet and presentation software and are used to syncing their data between their netbook and "the cloud".
It's not a replacement (today) for traditional, local OSs when it comes to CADs, intensive graphics manipulation, video editing, or gaming.
And being open-source means that it won't secretly track anything you do. Your ISP, on the other hand, will :)
