It's not quite as exciting as Windows Phone 7.8, but Nokia is rolling out some changes for North American Lumia 900 users. The new update, available today in the US and Canada, adds flip-to-silence, which lets users silence a ringing phone by turning over the device. It also should improve the camera and the phone's startup sequence. In the US, users should see improved battery use. In Canada, there are a few extra tweaks, like the self-explanatory Contacts Share feature that made its Chinese debut in June and a fix for the purple tint and proximity sensor problems that were corrected for US users in June. This update isn't coming over the air, so you'll need to have either Zune for Windows or the Windows Phone 7 connector on Mac to install it. A full list of features and instructions are available here.