I, for one, would find that behaviour distracting at least, and
probably quite bothersome. If it ever is implemented, it should be
possible to disable this.
In addition, given the huge number of possible window heights/widths,
and browser technologies, I would say that this will be difficult to
implement well (to say the least). Also, this is a presentational
issue, and as much as possible, presentation should be kept out of
HTML. It *might* be reasonable to propose this to people defining
stylesheet mechanisms (ie. I need a way to make text "sticky").
I would not like to see this part of any standard until an
implementation has proven it's value.