The existence of a delete button on my DSM-520's remote has lead me on a quest to discover its potential use. Digging around in the upnp spec (http://www.upnp.org/download/ContentDirectory%201.0.prtad.pdf) I have found some clues that deletion via upnp may be possible.
Is this a potential feature for MediaTomb, or is their some issue i'm not seeing?
adding and removing objects to/from the database is indeed part of the UPnP spec.
So far we have not seen any devices supporting this, so I never bothered with that feature.
Can you confirm that the delete key on the 520 indeed uses that feature? Maybe check with Twonky (I am not sure if they offer this) or Philips Media Manager.
I think deleting should be quite easy, support for adding objects is more complicated, but then again - I doubt that the 520 would support that anyway.
I was not able to find any information about it on the Twonky or Phillips Media Manager sites.
Is their any way for me to check the MediaTomb logs to see if its getting this signal from the DSM-520, even if it doesn't know what to do with it?
If you have a windows machine you could get Intel Tools for UPnP and use them to look at the supported UPnP actions.
Another way would be to download the cds service description from those servers and check if the function is offered, but I guess at this point it would almost be easier to simply install them and test vs. the 520.
Since those actions are defined in the service xml you can not check regarding "getting the signal" - the function invocation will only come if the service is defined and offered by the server, so you can not test it with MT at the moment.