Google has begun implementing codes in its browser, Chrome, to make it aware of the orientation of the device it is running on. This technology is built built into WebKit on which both Google Chrome and Apple's Safari are based.
This technology would allow the browser to use the device's accelerometer to orient the browser's interface properly. It will also be useful in certain applications as Google is planning to introduce browser based applications for Chrome (and Chrome OS). This feature has already been implemented in Firefox though.
This will be a very essential technology in Google vision of having the web as the center of user activity for its upcoming OS, the Chrome OS. Since Chrome OS will most likely be used in tablets (we hope), orientation of the UI according to the device orientation is an essential feature.
Yes Google is betting heavily on the web as the center of your activity and this feature is just one step towards realizing that.