I'll be getting the EVO once I get back from a month tour abroad.
Video Calling over 3G/4G
Presumably Easier Tweaking
Removeable Storage and Battery
Presumably Better Camera/Flash (two LEDs for the flash)
Thinner and smaller
Higher res screen
I doubt the iP4 will be able to take advantage of 802.11n due to device/memory lag.
Honestly, I really wish that HPalm would come out with a new device asap, as WebOS pwns both Android and iPhone OS in many ways; i.e. great multitasking and universal search. I also really like the touchstone inductive charging and a physical keyboard. Alas, there's no news of a new WebOS device and my Pre is feeling slightly dated compared with the EVO.