What exactly do Support Packs update? Netware, Zenworks, Groupwise???

One of my co-workers noticed that iPrint appeared to not get updated in a
recent SP update and he had questions regarding SP procedures.

Are there any individual updates on the Support Pack cd that need to be
manually installed in addition to SP?

I have been for the most part just doing SPs when they come. Sometimes
there have been cases where post SP patches have been necessary.

Thanks for you time and assistance in advance.