1. A method comprising the acts: analyzing first data corresponding to imagery captured by a user's smartphone camera, to yield identification data corresponding to a first non-human physical object depicted in the imagery, said analyzing being performed using electronic circuitry and comprising an image fingerprinting operation that includes (a) identifying candidate keypoints by convolving the first data with a blur filter to detect space-scale extrema of a scale-localized Laplacian transform of the image, (b) discerning and discarding keypoints having a contrast below a threshold value, said discerning including performing a second order Taylor expansion, and (c) checking remaining keypoints for matches with reference keypoints for reference physical objects; and issuing instructions that a social network graph data structure be updated to add node and tie elements, the node element corresponding to the first physical object, and the tie element indicating interaction by the user with said first physical object, information in said social network graph data structure being published by a service for viewing by one or more third parties; wherein the first physical object is identified by reference to the first data, and the user's interaction with the first physical object is automatically publicized to said one or more third parties.