Each of these modes is effectively an in-emacs application.
Jekyll and org-mode
Jekyll is a static website and blog engine. It's possible to write everything in org-mode in a single org file, as described in this blog post: http://endlessparentheses.com/how-i-blog-one-year-of-posts-in-a-single-org-file.html
Technically, it's needed to use his package ox-jekyll-subtree and then we just need to call M-x endless/export-to-blog to export the current org subtree as a jekyll entry post.
Pelican and org-mode
org_reader is a Pelican plugin to write posts in org-mode.
See more options within the Blog category: