The 'short' name of a site is just the cm:name property of the site node.
If you are using search service to find all nodes with type (http://www.alfresco.org/model/site/1.0}site ,cm:name is it's short name; If you are using SiteService to list all nodes ,then SiteInfo already has getShortName method. If You are using webscript api ,then returned json also has "shortName" property.
I am using the javascript api. is there still a method to get all the nodes with the cm parameter. Or is this only obtained using the webscripts methods