It seems hundreds of Twitter accounts have started to Tweet out “weight loss” product spam today.Specifically, users who have had their accounts hijacked are Tweeting the message “I lost 20 lbs in 2 weeks!” and links to diet sites. Our source counts over 200 rogue tweets so far tonight.It’s not just new users getting caught out: famous tech pundit John C. Dvorak (@therealdvorak) got caught up in the attack, and was none too pleased.