I noticed an interesting feature at the end of the Google Chrome OS Demo video today. Apparently, you can pass the URL of any publicly available PDF file to Google Docs and it will act as a plugin-free PDF viewer right in the browser.
To view a PDF file without any plugins, append the URL of the file to the end of the address shown here in bold type:
For example, here is the viewer displaying a PDF copy of a NASA publication.
I don’t think this is a new feature, but it’s the first I’ve seen of it. Google appears to use it to preview some PDF documents in search results (example).