What is Eve Online?
EVE Online is a player-driven persistent world MMORPG set in a science fiction space setting. Featuring seemingly infinite customisation on both your pilot and your ships and a huge world, it definitely is an unique game.
What makes it even more special is the fact that EVE Online uses only one "shard" - all players live in the same world (as opposed to many popular MMORPGS, where players play on different "shards" or servers). It also features a very "real" world, in which there is no "right" way to play - you can be a mercenary, a miner, a trader, a member of a giant alliance (where you work with thousands of other players towards a single goal) ... there are practically no game or moral limits (you can sabotage other players, or even scam players out of their money) - it's all legitimate and won't have any repercussions from the game developers / GM's, not that that can help you much when half of the player base turns against you.
Where is Python used?
Python enabled us to create EVE Online, a massive multiplayer game, in record time. The EVE Online server cluster runs over 50,000 simultaneous players in a shared space simulation, most of which is created in Python. The flexibilities of Python have enabled us to quickly improve the game experience based on player feedback
-- Hilmar Veigar Petursson, CCP Games.
Both the server and client software for EVE Online are developed in Stackless Python, which allows a large number of players to perform tasks without the overhead of a call stack used in the standard Python distribution. Going in depth about Stackless Python is out of the scope of this blog post (and my current experience), but if you think it would interest you, Google around for more info. You might also (or rather) look at PyPy which also supports stackless mode along with many other features. Even Christian Tismer, the creator of Stackless Python feels that "PyPy is much superior to Stackless itself and is the way of the future".
To tell you the truth, I have no idea how EVE Online plays (except that it apparently has many many lasers / disco lights in high-end battles :P), so just have a look at a random gameplay video I found on the web.