Vantage has no mobile version yet however there are plugins that can do the job like
WP Touch but it may need further tweaking either to the theme or the plugin for a full compatibility.
I believe the dev team is focusing more on enhancing the existing themes' features and so mobile version of the theme is not yet of a priority. Likewise, this has been requested at the ideas exchange page
http://ideas.appthemes.com/appthemes...ch-theme-1781/ of which implementation is dependent upon the numbers of users requesting and voting for it.
