I suppose this depends partly on who are one's associates. The people I play with here (Houston, Texas, USA) include probably 60% women, depending on the venue (more for old-time music, less for Irish). The men tend to be better guitarists and mandolin-ists but the women frequently blow them away on most other instruments (harp, autoharp, both kinds of dulcimers, upright bass, Chinese pipa, etc). Banjo-players, fiddlers, and singers are about split down the middle. We don't have a problem with the "eye candy" syndrome--we're all pretty much equally unsexy. Women also play a huge part in starting and maintaining the organizations that promote traditional music. Most women musicians I know of write (or research) their own songs and play instruments well.

Of course, even those of us who pursue music professionally are not nationally-known, for the most part.

As far as club performances go, I would say it varies greatly with different individual clubs and different genres of music. Some of the barbecue joints and kicker bars in my neighborhood rarely, if ever, feature women performers. On the other hand, a lot of them do. It probably depends on what interests the clientele. The best pub in town features plenty of women and a big range of types of music. The smaller establishments feature whoever they can get just to draw in customers (and yes, some of them, men and women alike, suck).