This disclosure describes a distributed reader architecture for a mobile computing device such as cellular telephone handset. One claim recites a method for identifying a content item from a host signal captured on a mobile telephone handset, comprising: from the handset, receiving filtered data from the host signal for use in identifying the content item; processing the filtered data to compute a content fingerprints; using the content fingerprints to determine an action associated with the content item, in which said determining utilizes information pertaining to an operating system associated with the mobile telephone handset; and communicating information associated with the action to the mobile telephone handset. Of course, other claims and combinations are provided as well.