All the cool MMO kids are coming to Steam. Star Wars: The Old Republic joined Valve's storefront this year, and even RuneScape is on Steam now. ArenaNet were planning to follow by bringing Guild Wars 2 to Steam in November, but have announced that its release is being "put on hold for the time being" as they focus on the forthcoming End of Dragons expansion.
Here's what the team has to say on their blog: "Our number one priority right now is crafting Guild Wars 2: End of Dragons with the high quality you expect and deserve. Additionally, we're full speed ahead on delivering an epic climax to The Icebrood Saga that lives up to (and we hope exceeds) previous Living World finales."
When the Steam release of Guild Wars 2 was announced earlier this year, we noted that existing accounts wouldn't be compatible. Meaning that you won't be able to bring characters you've already made to the Steam version if you switch, which is a shame. (If you've not played Guild Wars 2 before and are planning to give it a shot, or will be rolling a new PC for the Steam version, I recommend playing as a Norn so you can experience their starting area, the Wayfarer Foothills.)
Back when it first launched in 2012, Guild Wars 2 was our MMO of the year.