The G-7 still exists, as the post below explains. However, it usually deals with economics (the 7 nations ar the strongest and most powerful economically). The G-8 is the seven plus Russia (as others have mentioned), and it probably does have to do with the "dangerous weapons" theory.

http://www.rferl.org/nca/features/1998/05/F.RU.980512121951.html