Pretty much. (My strategy is to slice it in two on receipt, eat half, and take the rest home--harder if you're a tourist, though.) It's also safe to say that if the norm is 1/3 to 1/2 pound where I live, it's more like 1/2 to 1 lb. in, say, Chicago or Texas. (Not that you can't get a 1 lb. burger here--just not everywhere.)

"Sliders" are another burger trend--one plate of 2-3 small burgers on dinner roll-sized buns. I'm not sure what the total amount of meat is for these--I'm not good at eyeballing it, either--and the menus never specify, IME. Sometimes these are treated as a "small plate"-type option, others as an appetizer. You know, in case you need some burgers to warm you up for your 1/2 lb. burger.