It always helps a searcher to have some idea of what goes into the snippets. Heather Lloyd-Martin advises SEO writers and how to write content for best showing in Google’s snippets.

Updated: Google snippet trick tips for success (SEO Copywriting March 7)

• Title is always important
• Meta description is also important but Google will often ignore it
• Headlines can have more impact if they include keyphrases
• Keyphrases can have more impact if they are near key messages.
• Synonyms are a good thing.

Many more good points  in the article.

Also read Bill Slawksi’s article,  How Google Might Generate Snippets for Search Results (SEO by the SEA, Feb 25), for a more technical and detailed treatment of what Google is doing.

What’s important here is that Google does have a process in place to decide where it might take text from when it shows a snippet that isn’t from the meta description on a page.

And his follow-up article on Why Google May Change Search Result Snippets (March 3). A new Google patent shows how it may be creating snippets from results extracted dynamically – those “sesion-based dynamic search snippets”.  Basically, one can just marvel at the ingenuity of Google search engineers.