With increased use of large texture pages and mesh libraries, the 'pack problem' will occur. It will no longer be sufficient to download one item, as, if it is related to a library, the asset KUID will only contain the config.txt, the mesh is in the library which could probably be a multi-megabyte download.
This is where TS2010 is going.
The sign collection comment that started this thread will still be valid, even if that collection of a family of signs was in a mesh library for greater efficiency, there will still be multiple instances of similar signs to sort through, any one of which will entail downloading the library.
It may not be evident yet but a single multi-texture page with an associated normals page which itself has an alpha page attached, could easily be more that 7 mb, imagine how your file collection will blow out if every single item carries that sort of overhead.
Peter