The smartphone has not been on sale for long but already HTC has put together an update. We've got a One X at the PC Advisor office and can confirm the update bumps the device to version 1.28.401.9 and is a 23.85MB download. See also Group test: what's the best Android phone.
The upgrade brings no obvious visual changes apart from reportedly tweaking the auto-brightness for the screen. The One X has been branded with bad battery life across the web and this firmware update supposedly fixes this problem. Other bonuses include better performance and slight bug fixes like the menu button displaying incorrectly.
We weren't notified automatically about the update so if you have a One X then head to the settings menu and run a manual check. See also How to manually upgrade an Android smartphone or tablet.
Our model is SIM-free which often gets updates like this before operator models so be patient if the update isn't yet available. We're quite fond of the smartphone so find out why in our HTC One X review.