Forum Lore Quests are not announced in game, and although you might stumble on them by accident, they are leaked to the players by the devs in the SOE forums, hence the name. They usually fall into other categories as well.
On May 4, 2006, a Sony EQ2 player by the name of Cusashorn posted a curious entry in the Lore threads of the Sony EQ2 forums. Many people originally thought the post was merely a bit of fan fiction written by someone with lore knowledge of the Everling family of Nektropos Castle but it turns out it was a hint at the existence of the first of a new type of quest being added in game based purely on lore, especially obscure lore.
Dates of forum lore quests becoming officially known: