It worked, thank you very much.
Well, not exactly: parent is still parent and points out to the parent object of anything. What changed about parent is that now any first-level page item is the child of a Spread -- while it could be either the child of a Page or the child of a Spread before CS5.
Then, Adobe introduced in CS5 the wholesome parentPage property, which works at any depth in the Document hierarchy. IMHO that's the best improvement in the Scripting DOM since its birth ;-)
It's also worth pointing out a major functional difference between parent (in CS4) and parentPage (in CS5).
parent is the object which owns the PageItem, while parentPage is the page on which it draws.
The most practical difference is with anchored objects. If you have an object anchored to the right page of a spread, but it draws on the left page, working up through the parents will get you the right page. ParentPage will return the left one.