iirc the screen-down speakerphone uses the accelerometer and the proximity sensor, and according to
http://www.sizlopedia.com/2010/05/13...unch-june-4th/ the Evo should have both. TP2 used the prox sensor to turn off the screen when its up against your face, the light sensor was used to handle the auto screen brightness. I'm coming from the tp2 and I really hope the speaker doesn't suck. I always get a kick out of whipping mine out to play a youtube video that my friends are struggling to hear from their phones, then having to turn it down to 50% because its so loud.
*edited for crappy spelling