Nokia has released an updated firmware for Lumia 900 handset on US network AT&T. Addressing a number of small issues that have been highlighted through user feedback, as well as tweaking the colour tinting on the screen and proximity sensor issues, the update will be applied through either the Zune PC suite or the Windows Phone 7 Connector for Mac users.

Nokia's Conversations site details the three main areas of change in the update:

• Removes purple hue which affected the screen of some devices in low light conditions.
• Improved sensitivity for the proximity sensor.
• Other minor adjustments and enhancements.

Here are Nokia's "How To" videos for the update process on PC and Mac if you've not went through the process before and would like a guide...

More details can be found at Conversations by Nokia.