We stumbled across a minor update release for the Evo 4G, in RUU form. In an attempt to find out which files have been modified in the update, the XDA faithful have already cracked it open, rooted it, and are in the process of further exploration. Expect to see some new ROMs built on this update over the coming days.
According to XDA member joeykrim, this update brings changes to the kernel, Recovery.img, hboot, and many .jar files within the framework.
If you're rooted, it might be a good idea to hold off for a few days in case there are any surprises waiting in this update. But if you're feeling adventurous, go ahead and grab the rooted update and start flashing (your ROM). [via XDA, rooted version]