I hope this page comes up whenever someone searches on "metadata" in this SAIL space.
SAIL will be mostly agnostic to metadata. Entities within SAIL will have properties, such as to support link resolution and version history, but these are more primary data necessary for the functioning of the system.
Metadata, or data about data, will be attachable to SAIL entities in any schema. For example, a user will be able to annotate a pod with a LOM field and a Dublin Core field at once.
See also Pod metadata.