Can you please explain the difference between being crawled and being indexed?

Google are worried that links are not editorially given when they appear on my site. Whilst many of my readers agree with me that they are, I am going to comply with the letter of the law. I also happen to have nofollow where those same links appear on duplicate content pages using my nofollow dupes plugin.

If I wrote high quality on topics reviews which I always strive for, they are going to get syndicated.
I can’t prevent the splogs, but just like article marketing I can encourage legitimate syndication which involves an extra level of editorial control. Google can’t give a penalty for that.

Of additional interest is Tim’s research on PDFs, another loophole.