Again, I would like to mention that I want to have 200 ppi (100 ppi at a minimum) for the native download. That gives me the ability to scale down as needed. It is very difficult to scale up and maintain a nice appearance. That way if a group has someone with low bandwidth they can still use it, but if everyone has broadband connections they can benefit from the more detailed map.

It should also be noted that the various VTTs themselves have different ways of distributing their maps. MT actually has the ability to host directly from the GM's server or to pull from a webserver. A nice feature that was recently added. Also, the files themselves can be sent directly outside of the tool and the players can host them locally which allows the GM to distribute the needed larger files well in advance of the actual game time.