I've heard it used to describe someone who's tall as well as someone who's got an air of smug self-importance. But my favorite was from an old guy (as in, fought in the South Pacific in WWII) who used the term for someone who was famously cheap. "Ol' high-pockets Bruce didn't leave a tip, so I threw in a couple more bucks."
It's a lot of work to reach into those high pockets.....