Wizards of the Coast, in The Year of the Dragon, will have several events to celebrate play, including short adventures meant for a single game session--starting with Descent into the Lost Caverns of Tsojcanth.The Lost Caverns of Tsojcanth was a 1982 adventure by Gary Gygax for AD&D 1E, and was set in the Greyhawk campaign setting. It featured a wilderness journey and two-level dungeon, at the end of which the PCs would face the vampire Drelnza, who was the daughter of the archmage Iggwilv.
No news yet about any others or how many there will be.