The "HD" in "HD Radio" doesn't officially stand for anything. It's a marketing ploy, and a reasonably smart one since both stations and listeners have taken it to mean whatever they want it to mean: "hybrid digital", "high definition", etc etc.
Target carries the Sony tabletop HD Radio receiver with a built-in iPod dock. I don't know if they actually sell 'em in stores anymore, but
on their website it's $180...a steal given what a fabulous receiver it is (one of the best).
I have several Boston Acoustics Receptor HD units in my office and house. They're so-so on AM but,
with a proper antenna, quite good on FM. Unfortunately, BA discontinued them several months ago. Maybe on eBay? :-\
Radio Shack sells in-store a Jensen HD Radio that also has an iPod dock and supports iTunes Tagging, which is pretty cool. I don't know how good a receiver it is but presumably it's pretty decent; most HD Radios have proven to be good receivers when you've got a decent antenna attached.