Currently the RadTileVIew supports all kinds of dynamic changes to its items(adding, inserting, removing etc.) so the first part of your scenario is easily achievable. As to the second part, the saving of each individual's preferences, at the moment we don't support it out of the box, but we're planing to release a Persistence Framework for the Q2 2011 which will help you with this.
If you have further questions feel free to ask.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!