The RSS feed generator should honor the `<!-- more -->` tag, displaying only the excerpt in the feed with a link to read the whole article. This is the expected behavior.
When I use the Excerpt `<!-- more -->` plugin, I would expect that this also be honored by the RSS feed generator. Only the excerpt should appear in the feed, along with a link to click through and read the whole article. This appears to be Jekyll behavior, so maybe I should open the issue over there. One cheap trick I had in mind was to have a post-generate task alter the atom.xml file to strip out content after the `<!-- more -->` tag for each article. I am open to suggestions and I'm willing to work on this issue if you think it's useful to Octopress (or Jekyll) users in general.