I'm implementing a draft of this in Aperture right now. Here is the current API.
Every entry now includes a unique system ID, meant for internal identification of the item (not global identification). This is returned in the timeline response as the parameter _id, and there is now also _is_read. For example:
These new _id values are meant to be opaque to clients, and must always be a string. Some servers will likely use integer database IDs, but other servers may use other string identifiers for entries depending on the implementation.
Retrieving the list of channels now also includes the number of unread entries in the channel:
I should add that the `_id` values are meant to be an identifier for this instance of the entry in the channel, not an identifier for the entry across channels. This means if you're following the same feed in multiple channels, entries may have a different `_id`.