For those that are curious a very rough breakdown of what each type of kana is used for:
Kanji - Meaning of the word
Hiragana - Grammar
The Hiragana parts of "words" are usually the parts you change when you inflect a verb or adjective... I wouldn't say Hiragana's purpose is soley grammar though.
QUOTE said:university uses these for their 'Japanese for Business' courses, which are a cut down versions of the full blown Japanese course.
The Japanese names for these books translates "Japanese for the pupose of communication", which is exactly what they teach.
If you get hardcore into Japanese you should get some of the advanced books published under the power japanese series, published by tuttle now, these will make your brain explode.
As I said, those were very rough explanations, I'm sure someone with a better focus on linguistics could give a much better explanation as to what their functions are directly. That said, inflection and particles (other than the basic spelling of words, which often get changed anyhow) are the main areas where hiragana is used, hence my associating them with grammar.
As for the book, I've personally never seen them. My university's japanese business course is only 2 sessions in length, and as far as I know has its primary focus on vocal communications rather than writing.