Currently, arc land does not provide a convenient mechanism to land commits authored by others (e.g., someone who is not authorized to commit to a project; someone who is out of the office) while preserving authorship information. Currently, if I apply a patch with arc patch, then use arc land to land to the repository, authorship meta-data is not preserved. On IRC (https://secure.phabricator.com/chatlog/channel/6/?at=110908), @epriestley suggested that his workflow was something along these lines:
git checkout master arc patch -nobranch D### git push
This is simple, but nonintuitive.