When you are looking for PDF files, Google now displays authors of the PDF file and publication date. Only when it is available.
google.com/search?q=site%3Amem ...

It may be related to Google Scholar ("cited by...")
google.com/search?hl=en&q= ...

Have you ever seen that before?

Ionut suspects the data source for this to be Google Scholar:
googlesystem.blogspot.com/2008 ...

I can't see the author's name in the examples mentioned above. Seems not to be rolled out to everybody.

Update:
I don't see the author's it in the example query results but it in other result pages. It seems to depend on the search, if you can see the author.

For example I can see it here

google.ch/search?q=site%3Asta. ...

but not here

google.com/search?q=%22h%C3%A4 ...

even if the first result is the same document.

I see it on a .htm result when doing a search for BMI.

google.com/search?hl=en&q= ...

The result from the CDC shows "by P Room", which could be Press Room as I couldn't find a P Room anywhere on the page.

I don't like this function. May not be that useful as many documents don't use real authors. I hope that they've got filters for the most popular writers of our century, e.g. 'GoLive' and 'Administrator'. ;-)

Works here, and absolutely this is a new feature.

When searching with Google.fi the text is localized too:
"kirjoittanut P Belhouchat – 2004"

It appears that Google can digg the year document was saved too

This feature seems to work with PDF, PS, HTML, Doc ...

[PS] google.com/search?hl=en&q= ...

[HTML] google.com/search?hl=en&q= ...

[DOC] google.com/search?hl=en&q= ...

This must be a Google Scholar feature that was pushed to Google.com searches this month.

Not only PDF files.

(I added an update, thanks!)

This has nothing to do with the PDF/DOC/HTML files. Google uses data from Google Scholar to improve the results for scientific paper.

Some people thought Google uses metadata from the files: businessol.com/seo-blog/2008/0 ...

Ionut, where does the name "H Another" come from? (I show it in the update.)

Well, these links might provide an answer:
scholar.google.com/intl/en/sch ...
scholar.google.com/intl/en/sch ...

"We rely on a document's layout to extract metadata, citations and other information which plays a significant role in relevance ranking."

H Another is most likely the result of a bug. As you can see from this search: scholar.google.com/scholar?as_ ... Google doesn't find the author correctly all the time. There's an author called "H another error enters Diffey’s" for a text that includes in the middle:

"However another error enters Diffey’s calculations when he assumes that 600 to..."

There's another author called "HOMLT Another" from a text that includes "How One Mistake Leads To Another" as part of the title.

img135.imageshack.us/img135/73 ...

I can imagine that Knol's "Real Names" will appear in this field in the future.

Another weird result:
google.com/search?q=css

img137.imageshack.us/img137/10 ...

More examples of papers: google.com/search?q='Citing+Ar ...

The example search
 blogoscoped.com/forum/138085.h ...

comparing Google.ch and Google.com gives the author information here, when using Google.com link too.

A similar feature that I just saw-- is Google treating forum results differently? For example, when I search google.com/search?hl=en&sa ... , I get results that say things like "20 posts – 8 authors" at the top.

I can't see these post & author information with the Google.com test URL listed from my country