http://fab.wmflabs.org/maniphest/task/create/ in "Projects" has "Type a project name..." as placeholder. This is not helpful for those who don't know what a "Project" is, for instance Wikimedia users will enter "Wikispecies" or "Latin Wikipedia".
Better use a couple examples: Phabricator could automatically use the first two most used projects, or it could be made configurable.