Google did two things today which can be considered slightly evil. They rolled out a new search result page. Which killed instant previews and shortcut to Google Docs Viewer for document files that appear in search result pages.
Using this shortcut, you could get a quick preview of the file (pdf, office files etc) right inside the browser.
Apparently, the timing was planned as Google launched Chrome Office Viewer just a few hours later. Chrome Office Viewer is a Chrome app and it offers a similar functionality. If you have this app installed, you can view Microsoft Office files right inside the browser.
The problem is that this extension is not available on other browsers. And it is unlikely Google would release it for Firefox and Internet Explorer. Baaaaaad.