One of the concerns I had mentioned a long time ago is regarding the expansion of the iWork group of programs. The main thing is consistency.
I've touched on this particular subject before
I called it the iWork Core libraries. Brian Peat has suggested using the term Layout Core Libraries, which is perhaps better because it expands it to other uses, not just iwork.
When Pages first cmae out there were some distinct behavioral differences betweek Keynote and Pages. Keynote extended the capabilities while Pages just maintained the old capabilities. It was frustrating to have one thing not work between programs.
As iWork is expanded, this difference between programs, and the haphazard advancement of capabilities will become more pronounced. They should take the time now to start a new team whose goal is the maintenance and advancement of the capabilities of the underlying libraries for all these programs that manipulate graphical and textual data. OUtput and exports could also be integrated within them.
Eventually this may make it to the Mail program. It could even be used within a database program. A Graphical program or even as the underlying output generator for shared information (a scientific program whose data is laid out and out, allowed to be formatted and exported to Pages or Keynote even though it was ca third party program. Imagine the possibilities)
Anything that manipulates data in a consistent fashion could be in such a library. Having them codified would make updating the software easier as well since the developers could concentrate on the inherent aspects of the program without having to reinvent the wheel for each program under development.
Whether or not those libraries are made publically available is entirely up to Apple, but imagine what the possibilities if they were.