Update: Here's HTC's official statement regarding the update, which elaborates on the changes in greater detail:
As part of our ongoing commitment to ensure customers are receiving software updates that improve their user experience, we are pleased to announce our next upgrade for the HTC One X will be released on August 10th.
The primary update will include an upgrade to Android version 4.0.4 (Ice Cream Sandwich), in addition to an improved Sense experience which will: enable the ability to map menu function to the 'recent app' key (improving visual presentation in non ICS apps like Facebook); improve tab management in the browser with a dedicated tab switching button and enhance camera capabilities such as white balance and continuous autofocus. Furthermore, customers can expect enhancements to memory, platform stability and the overall browsing experience. Other improvements include a Single Sign-On for Facebook allowing user access across applications and browsers and upgrades to Beats audio, which reflect our dedication to providing an authentic sound experience.
From a developer perspective, we are expanding SDK support for Media Link and providing a framework for video call applications to achieve improved performance and quality.
According to German site HTCInside, the European variant (not confirmed for all regions) of HTC's One X smartphone is receiving an OTA software update to version 2.17.401.2. The update, as shown by the dialogue on the device (and our rough translation), promises Sense 4.1, Android 4.0.4, improved stock browser performance, and enhanced camera quality.
Having been using a Sense 4.1 ROM myself the last few days on my own One X, I can also confirm that the newest version of HTC's UI overlay brings at least one change of its own. Expect marginally smoother homescreen switching animations (the animation itself is a little different, too). That's actually the only visual Sense 4.1-specific change I've noticed.
Otherwise (and probably most importantly), the update includes the same recent apps button menu in Settings that we saw come to the AT&T version of the One X last week, meaning that annoying virtual menu button can finally be banished back into the nether regions from whence it came.
If you're getting the OTA on your One X, be sure to let us know in the comments!