That's the question being asked by the frighteningly excellent jihadica.com.
Citing an Al Qaida statement, they say: Abu Dujana al-Khurasani (real name Hammam Khalil Abu Milal) 'the famous propagandist and writer on the jihadi forums,' carried out the attack in Khost which left at least eight Americans dead.
The news that the suicide bomber was a regular contributor to jihadi forums has apparently caused a frenzy on message boards.
Jihadica say the incident "is sure to galvanize the online jihadi community, and would represent the most dramatic case to date of the potential for virtual-to-actual jihadi activism".
