I work on a construction site for 90% of my job. I install voice/data cables, and typically am on the job around the same time that the drywall guys are finish sanding. I've dropped the phone once from hand level to the concrete floor, no damage that I could see once I put all the pieces back together (battery door, and battery came apart from main unit).
My phone lives in my right front pants pocket, with the screen towards my leg. I tend to not take the phone out while doing tasks that would cause it to get hurt, and I try to get my hands at least fairly clean before touching it. I have answered it and been on a conference call at the top of a 12' ladder though. So far I've had the EVO about 4 weeks now. It replaced my Blackberry Bold 9000 (the one with the older trackball). I had to replace the trackball about every 6mo or so due to it getting gummed up with drywall dust. I'm hoping that the touchscreen eliminates some of that problem. I'm already in the habit of removing all pieces/parts from the phone that easily can be removed, and blowing them out with compressed air on a regular basis. The screen gets wiped down with a micro-fiber a couple times a day (usually breakfast, lunch, and nighttime). So far no scratches, dings, or dents.
I'll be sure to report back if something does happen to it. The company has offered to pay for an OtterBox for it, just not sure I want that big of a box/cover/case riding around in my pocket all day.