Hi there.
I brought up a similar question about the "People" application on our 5340e sets. Lengthy discussion (and some investigation) with my VAR leads me to the conclusion that this is storage that is -only- in the phoneset. We couldn't find any way to back it up, move/copy to another set, or even easily delete the data in the People app, from or to MiVoice/Collab. The only saving grace here is that our 5340's also have the regular Phone Book, but with no way for users to modify it. It doesn't help things that it's so easy to add callers from history "to People."
From a security perspective, this scares me a bit as well - let's say a user stores some secure/private stuff in People, and then perhaps the user leaves or the phoneset gets assigned to another user... I would have assumed that provisioning the set as new would delete all the data on any set, but it doesn't. The People entries must be removed one by one on the set itself. I have yet to find any way to -completely- wipe a whole phoneset.
I hope I am wrong, and there is some other solution, but this is the best I could come up with.
Cheers,
-dg