Agreed, author and last modified is irrelevant.

About the summary, the problem is that the search results show the "Description" field, which is being left empty in most pages. It would be much better if it would show the beginning of the text or (ideally) the excerpt around the keyword searched as Google does.

Ramon, what can be done about this? 

The Description-Field of every Content-Object (Page, Folder, File, Image ...) is used for the search results, folder listing and the html-tag <meta name="Description" ...>. It's important to use it.

In the default-template, the Description is shown when you view a Page, between the heading and the text. This forces people to structure their text with a kind of introduction which does not work all the time, write a improper description that is bad for the text quality or ignore the Description-Field.

The best solution from my Experience is:
- require the Description-Field
- Remove it from the pageview-template
- Add an Introduction-paragraph-format to the wysiwyg-editor

Sometimes you need to duplicate the introduction, but you can decide what's the best intro for the text and what's the best description for listings etc.

Fixed in http://dev.plone.org/collective/changeset/77884

- make description required for every content type and add a better description 
  in the edit forms.
- add an 'Introduction' paragraph style (p.intro) to the rich text-editor (kupu)
- remove the description from the view template for all types with an rich text 
  field (Page, Event, News Item) in favor of using the 'Introduction' paragraph 
  style. The description is still used in listings, search results and the html 
  header.