Yes you can, but only with the people within the Vita detectable range and the Wi-Fi range.
I am sure the social feature are updated by other users PSV sending feedback of their position via wifi or 3G. So if you have a wifi only version you will be able to see where people are in a range further than your own wifi range, others peoples location will be populated on Sony's servers and fed to you through the hotspot you are connected to
The inaccuracies in the system will be wifi only models knowing that they are connected to a hotspot and are within the radius of its reach (which can be a big area when you think about it) but not exactly where in the radius. Only the 3G models will give accurate positioning.