We found that newsletters are a spectrum ranging from the traditional graphics and html emails to just using the community. One common process is to use the community as the place where the article authors go to create their items. The newsletter editor gets the initial part and the link to the full article in the community.
Using a community also enable you to a change to a newsfeed instead of a historic document. Using a community, we just send an email telling folks the new version is live and providing a link to the community. We are using RSS feeds and tags as a way to sort and categorize the articles.
Publishing in a community also allows other newsletters to leverage the articles.