I have been trying to slay this thumbs up meme for two days, thanks to damned Sean-Paul and Max and atrios.
Yes, the thumbs up did at one point in time 9and in many places still does) mean something negative. However, since the first gulf war, the meaning has changed for many living in the region. The folks at the Defense Language Institute have this to say about the thumbs up sign in their most recent manual:
Thumbs up- This gesture, expressing connotations of “I am winning,” historically is offensive to many Arabs. After the Gulf conflict, however, Middle Easterners of the Arabian Peninsula adopted this handmovement, along with the OK sign, as a symbol of cooperation toward freedom.