Indeed they do not! Here is the link to the IATA airline membership list. They conveniently make it searchable for anybody to use. Anybody who took it lightly would not make the list so easy to use:

http://www.iata.org/membership/Pages...bers_list.aspx

Many IATA rules and much other information is publicly available on their website. They a=make it easily available partly in an effort to make the travelling public perceive value in the membership, thus acting to reduce the erosion in IATA membership recently, especially with LCC's.