Yes, each user has his / her own laptop.
If I'm understanding the term correctly (portable) the list would need to be portable.
If I logged in to my 'account' from my work laptop while on the road instead of my tower at home then I would need to see the same list as I would see from my tower with the program list in the same state of "already watched" and "not watched yet".
If my daughter logs in from her friend's computer and watches some Big Bang re-runs, then she would need to see her same list, as tailored to her past viewing, when she is on her own computer.
I see it similar to a forum site like this insomuch as the website / account remembers posts that a user has read / visited before, remembers the posts that a user has made and so on the home media server I would like each user to have a customized list based on what has already been watched and this list is the same regardless of from where the user logs on.
For an added bonus it would be nice to have the system remember a partially watched / interrupted episode and restart that episode from where the user left off.