This script will get the Packages, Categories, and items associated with a Virtual Guest.
require 'softlayer_api'
require 'pp'
client = SoftLayer::Client.new(:timeout => 120)
virtual_server_id = 26961063
object_mask = 'mask[id,fullyQualifiedDomainName,billingItem[id,item[id,description],category[name,id],children[id,item[id,description],category[name,id]]]]'
getDetails = client['SoftLayer_Virtual_Guest'].object_mask(object_mask).object_with_id(virtual_server_id).getObject
pp getDetails