If the majority of the article is still copied Google can definitely pick up on that.

As you know, Google indexes and saves a copy (cached version) of all pages it crawled and indexed and its an intelligent search engine and easily finds it if most parts of articles are the same. You can't expect that Google doesn't detect it by changing some keywords from an article.

Google can easily find duplicate content, so it is best to submit original content, especially on your own website...

This sure explains it better than I can...
Duplicate content - Webmaster Tools Help

Nice link John. I've not seen that before. Very helpful.

I wonder how blogs are treated that quote portions of an article (with source link) for discussion purposes?

Rich