authentication needed for persistence?

[ronman]

According to the docs, using the persistence API requires
authentication:
http://code.google.com/apis/opensocial/docs/gdata/persistence/developers_guide_protocol.html

I was hoping to use some simple persistence to improve performance.
When the user adds or deletes a friend then i do something on my
server. Otherwise, do nothing. Caching for this case with refreshes
every half hour or whatever would be crude and wasteful. I just want
to check the Activities, and if a friend has been added or removed,
store a single value using the Persistence API telling the gadget to
run to the server and get fresh data.

But if a popup is required for user authentication, no one is going to
want to authenticate a gadget every time they login to the container.

Workarounds, other approaches?

Ron