Natural Language Processing or NLP for short, is an extremely powerful influence to relevancy.
Just remember that it does not ever replace good basic optimization factors, but it is something that you can study and apply to specific pages for those occasions where you have very low KEI (Keyword Effectiveness Index) phrases, that are highly competitive.
NLP is an influence that is at work in the background rewarding you for writing higher quality, (well written) content.
When you hear Matt Cutts from Google talking about writing better quality content, he is not offering deep hidden meaning in his advice. There are EXCELLENT reasons to write higher quality content that reads well to your visitors.
Best advice is to create content that is useful, reads well and that serves some legitimate purpose.