Via
Slashdot, an intriguing
PowerPoint presentation (PDF) analysing spam, and using techniques to determine its origins. Among other claims it makes, spam intended to sell things is in the minority, and a lot of spam consists of other spammers' ads, resent to either identify valid recipients or to act as a carrier for encrypted messages between IRC groups. (It doesn't say anything about al-Qaeda terrorist cells or the like, but one imagines that if someone want to send coded instructions to covert operatives without disclosing their locations to traffic analysis, this would be a hell of a lot less conspicuous than mailing a Hotmail address accessed from a net café in Baluchistan or someplace.)