I personally know a lot of guys with Hemis with 150k plus on them and I can think of one with over 200k. It's only been out since '03, so it'd be a bit harder to find a lot with 200k plus miles on them.
Given their record with truck motors, I've seen 318s (5.2), 360s (5.9) with well over 300k miles on them and some 4.7s with well over 200k miles on them. It's a safe bet that with decent care, you could expect 200k miles out of a Hemi.
That said, I have a favorite saying: Dodge trucks: best engines on the planet, matched with the worst transmissions!!!