The WiFi Scan is a site survey tool which acts in much the same way as your laptop wireless scan does. It does not show you devices, it shows you networks. Even if you are within range of several mesh nodes, they are all part of a single network called HSMM-MESH. You will probably see other network access points there as well.

If you are interested in what other nodes are visible from your location you need to click on the OLSR Status button on the main page. From there, either the Routes or Links tab will show you which other nodes you can communicate with.

Another way to see what nodes are visible is to use the olsr-topology-view program. It provides a graphical display of which nodes can see which other nodes. At this time it is only available for Linux systems and it can be downloaded from the software download page.