It hasn't been officially released yet, but an updated version of Gmail (2.2.1) is out and ready to replace the existing app on your HTC EVO 4G.
Among the new features are improved performance in most areas of the app and a revamped header that makes it much easier to reply to and forward messages. This latter improvement addresses my biggest pet peeve about using Gmail on the EVO; the most commonly used action buttons (reply, reply all, forward) are finally not pinned to the bottom of the message anymore. They're all accessible through a new arrow icon at the top.
This subtle change makes such a tremendous difference in usability and intuitiveness, as it was always such a pain to scroll to the bottom of those crazy-long emails just to send a quick "Yes" response. The redesigned header alone is worth the upgrade to me.
xda-developers] Thanks, Brian!