When the first footage of XCOM's combat spread across the internet, I read several comments comparing it to Valkyria Chronicles, Sega's tactical RPG from the distant year 2008. I only ever played the demo of the game but that will change when it finally makes its way to PC, although when exactly that will happen isn't clear. Sega have confirmed that the port is real and that more information will be available 'soon', but that's all for now. Rather than being strictly turn-based, Valkyria Chronicles uses a system called Battle of Live Tactical Zones (BLiTZ), because it's much more rad than your grandpa's tin soldiers.
BLiTZ lets you line up headshots and run around as if you were playing a realtime game, but movements, attacks and support moves are limited by action points. The system works well but a quick straw poll (I emailed a friend who loves the Valkyria series) suggests some of the RPG story elements might intrude on the tactical planning, with missions occasionally changing course to incorporate scripted narrative events.
Still, I'm keen to play Valkyria. If only there were some sort of Fire Emblem anthology headed our way as well.