That's a good point. I decided to check out Wikipedia so that I can get my terminology straight. (Wikipedia is always right, right?) The mod is in beta, because the general public is can play it and is encouraged to offer feedback. But I haven't instituted the feature freeze commonly associated with betas; actually each new version has a lot of new features. So much so that I don't think it's a hotfix either, which seems to be primarily a fix of existing content.
So in conclusion, I have a beta with new features added every ten days or so. I think I'll call these "content updates," and I'll keep a version number on them so that if people have problems I'll know where to look.