UPDATE: Blizzard has provided the following response to the supposed leak:

"As always, we appreciate the interest in Blizzard’s current and upcoming games, but we don’t comment on rumors or speculation and we don’t have any new announcements to make. Right now we’re fully focused on the upcoming launch of World of Warcraft: Cataclysm, and we’re very much looking forward to celebrating that event with players around the world starting on December 7."

ORIGINAL STORY: Virtually no one in the industry is as tight-lipped about when they plan to release games as Blizzard. After building up a reputation for taking as long as they need to work on a game before releasing, the triple-A developer has gotten into the habit of not revealing an official release date for games until mere months before they launch. Though this ensures that gamers won't be disappointed by delays, it also leaves us wondering when they plan to release some of our most-anticipated titles. A new supposed leak may give us insight into their planned release frames.

The image above, supposedly detailing Blizzard's planned release schedule from now until the end of 2014, was leaked to MMO Game Site by a source "speaking on condition of anonymity." There are a few noteworthy potential releases on the list:

-Battle.net map market launching in mid-2011
-Battle.net "third parties" launching at the start of 2012 -- possibly meaning third-party releases available for download on Battle.net or using Battle.net for matchmaking? A Steam competitor?
-StarCraft II's first expansion as well as something called "StarCraft II Phoenix" coming at the end of 2011. The second StarCraft II expansion planned for beginning of 2013
-Diablo III releasing at the end of 2011 with two expansions planned
-World of Warcraft launching in Brazil in mid-2011, with a fourth expansion in mid-2012 and a fifth expansion at the end of 2013. Also some mystery project called "WOW TOG"
-an unannounced project called Titan launching at the end of 2013 (presumably this is Blizzard's unannounced MMO)

So obviously this list should be taken with a fairly large grain of salt. There are also a couple of big reasons to question it:

-The WOW movie is listed for the end of 2013. For a project that keeps starting and stalling, it seems unlikely that Blizzard would be counting on its release for a specific timeframe, much less listing a product that's not technically theirs on a product slate
-With Cataclysm's release next week, we'll have received a somewhat shocking two Blizzard products launching in a single year. That's pretty awesome, but this calendar suggests that we'll get something along the lines of eight Blizzard releases over the next four years. As a fan of their games who has to live with the speed that they take to develop, I find that pretty difficult to believe.

Even in the case that this planned schedule is legit, these releases obviously aren't set in stone, which is why they aren't officially public, so don't be shocked if nothing ends up releasing quite like it looks here. In the mean time, I've reached out to Blizzard to see if they have any official comment on the supposed leak.