Now, we should clarify two things. First, this tipster isn't one we have particular reason to consider reliable, though there is a link to DARA in the leaked image, an internal Sprint web portal. It's certainly a real possibility that this is from inside Sprint. The wording and formatting of the page also looks legit to us. Second on the clarification list, there have been previous "leaks" from Sprint suggesting the EVO would be receiving 4.1 on X date, that have later turned out to be false. So, as always, take it with a grain of salt. Without further ado, the image:
According to the page, the update includes just what you'd expect - all the Android 4.1 trimmings (Google Now, expandable notifications, etc.), along with Sense 4+, which brings improved front-facing camera performance and a new gallery app [which I hate]. Wi-Fi authentication, personalized ringtones, and various other areas have seen bug fixes as well. The new version number is 3.15.651.16 - which is in line with HTC's Jelly Bean update version numbering scheme used with the One X.
Again, while we can't be certain this is the real McCoy, we're leaning on "legit" here - the timing's right, and nothing seems particularly amiss.