This isn't quite the idea of MMO-to-go yet, but it's the first step towards something really huge in MMO gaming: a character API. An API is an Application Programming Interface-- basically a document or method of how to get computers to talk to each other through different applications. Facebook apps are made with the Facebook API, applications that hook into iTunes use the iTunes API, and so on. With an API, programmers can take information from one source, and do almost anything they want with it in other programs. Players have already done some amazing things with World of Warcraft's Armory (even without an actual API-- I'm pretty sure most of that is just HTML scraping), but now NCSoft's Dungeon Runners has upped the ante-- they've made all the character data in the game available to anyone as an XML file. With just a URL, you can access info on any player in the game, already marked up in XML.
What does this mean to you as a player? It means that programmers can create any number of applications using this data-- they can display your DR character's info almost anywhere at any time. And a skilled programmer could even track the info over time-- tell you how fast you leveled, how often you change your armor or gear, or how fast you've earned gold in the last day. And who knows what else people could come up with-- the best part about opening up information like this is that it gets used in all sorts of ways that no one could ever predict.
Jeff Freeman's exactly right: "This is really cool... just in case you don't get that." We're just scratching the surface of this stuff, but eventually you'll be able to do things like get text messages on your phone when your WoW auctions sell, or be able to monitor your guild's bank or your PvP team's wins via RSS (which itself can then plug into almost anything) When developers break out data like this for players, the possibilities are endless.