A Folkopedia discussion group is planned.
The Village Music Project is the basis for the [Tradtunes discussion group] although the discussions are not limited to the manuscripts published by the project.
Melodeon players often discuss matters of interest to them at Melodeon.net. This site hosts some lively discussion and lot of useful information for folks at all levels of expertise.
Anglo-American talk happens at Mudcat
Uk folk/acoustic and roots music is discussed at uk.music folk