Hi,
You can add an aspect to a folder/space using the Java API but currently there isn't support in the web client to show these or indeed to add an aspect to a space.
It would be fairly easy to add them though if you don't mind writing some custom JSPs. Just take a look at projects/web-client/source/web/jsp/dialog/document-details.jsp and edit-document-properties.jsp for an example of how it might work.
