My heart still goes pitter-pat for Cyan and the Nokia Lumia 900. Nokia has released a firmware update for the US ATT version, and it's just a USB cable session away from being yours. Plug you phone into your Windows PC running Zune software or to your Mac running Windows Phone connector and tell it to look for updates. I updated my Lumia using a Mac and all went well.
This update brings the following enhancements:
▪ 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
This update is only for Nokia Lumia 900 on AT&T’s network in the United States. In addition to the enhancements mentioned, Nokia says they'll roll out new updates and surprises in the near future to all Lumia 900 users.