Sprint released an OTA update for the HTC EVO 4G today. This update has fixed a few bugs, including issues where the touchscreen would not work if the handset was not being held (on a table, desk, etc) and faster WiFi speeds. It has not been confirmed yet if the faster speeds are due to the 802.11n being enabled with the update. To grab the update, go to the System Updates settings under Settings.
There are reports out there of this update bricking phones though; most claim that a 2nd update tries to come through after the first is finished, and opening that one is making phones totally unusable. So word to the wise; one phone, one update! Oh, and for those of you who have hacked or rooted your phones, this update does not play nice with those at all, so steer clear.