"As you may know, Guild Wars does not have a subscription fee of any kind. Players may choose to support future development of the game and expand their own playing experiences by purchasing new chapters of the Guild Wars story. These chapters will be offered about every six to nine months, and will be competitively priced. Unlike most "expansion packs," the new chapters will be approximately equal in size to the initial chapter of Guild Wars." Direct Link
Guild Wars was offically released to North America and Europe 28 April 2005 (News Link)
Expect the expansion in January-Febuary at the latest, notice they mention SIX to nine months. Kind of kills the 5-month rumor floating around.
It has, and this is still only general speculation. May come out sooner or later, most likely later. Till I hear something from A.net official via a press release, I will keep awaiting.