I certainly love the features, speed and ease of use of yEd and discovered it's use for visualizing our network.
We have a racktables instance providing all the layer 3 (IP) data. I wrote a custom software generating a graphml dialect with the minimum necessary "y:" and "yed:" tags to embed all required style information in a yed-parsable way.
If you are interested in a showcase, I might be able to provide an anonymized sample (Confidentiality concerns not withstanding).
I would be content to use the stock icons for network and server, but there is no suitable icon for a VM or an arbitrary network component (eg. print server, ntp source).
*** Am I allowed to export a suitable icon as svg, modify it in inkscape and use it in a diagram which itself gets redistributed (possibly company wide)?
*** Am I allowed to embed the manually extracted svg resources from the stock palette in the generated graphml in the first place (generate the required <data> section)?
This is no showstopper as I could use arbitrary vector shapes (according to their license, of course), but the quality of the stock icons is very nice and they look consistent and fairly appealing (to management/techs alike ;) ).