It's not clear to me whether anything that actually has to do with the game itself has a positive effect on social skills. Since much of any given game tends to boil down to solving a problem with a spell, a sword or a firearm, I would venture that most lessons learned in-game have little benefit back in the real world. Campaigns that are roleplaying-intensive may have some benefit, but the jury's definitely still out on that one. Of course, the ultimate social gathering of gamers is the convention. For those of you who haven't been to one of these unique events, they're not for the weak of heart.
Cons are normally three days long and take place in hotels.
Escapism through roleplaying is underrated. For the populace at large, it's far more acceptable to hide from life's troubles at the bottom of a bottle than through the expression of imagination. This is because members of society has seen the wrong side of imaginitive escapism. I know that this isn't the norm, that the vast majority of us aren't like that, but when RPGs get bad PR it affects us all. My own escapism benefit ties into the social aspect of gaming.