It’s one thing to rank pages based on publically posted links, another thing to use supposedly private links in emails or subscriptions to improve ranking quality.

This article on Problogger describes a recent Google blogsearch patent filing:

Is Google Reading Your Mail?!

Read this carefully:

[0044] References to the blog document by other sources may be a positive indication of the quality of the blog document. For example, content of emails or chat transcripts can contain URLs of blog documents. Email or chat discussions that include references to the blog document is a positive indicator of the quality of the blog document.

Are you thinking what I’m thinking?! Google has a massively popular hosted email service - GMail. They also have Google Talk, a chat service. You probably knew that. But did you know Google has intentions of crawling the content of your GMail emails and Google Talk chat sessions?! Now, I don’t know if they actually do that or not, and I haven’t gone hunting thru their terms of service seeking clarity, but their stated aim is clear: to find URLs in two key forms of personal online communications (email and chats), and to use these discoveries to further rank blogs and blog posts.

I have to say it makes perfect sense. Why? Because Google is looking to build a more and more accurate profile of your and my blog. And to do this Google wants to see corroborating evidence of popularity across as many different “media” as possible: web pages, blog posts, search results click patterns, blogrolls, social bookmarking services, and now email and chat session content. Wow… that’s called being thorough.

Using links in email to improve the quality of blog searching might seem harmless, but this is a real slippery slope.    

As automated analysis of natural language improves, and more and more services come under the Google umbrella, the possibilities for conflict of interest and abuse grow more numerous.  

When does mining private data for public use go too far?  Could Google mine emails for private stock tips and use those to create a public portal of investment tips, for example?