tedster - 4:44 pm on Jan 12, 2010 (gmt 0)

Normally we would not discuss methods used on a specific website by name. But in this case we'll make an exception, partly because Amazon is such a major company. I removed the specific URL, however. Amazon does this "sort" treatment on a variety of pages.

The key to understanding it is this -- it is not a good idea to allow Google to index different "sorted" versions for the same list of product results. It creates a kind of near-duplicate content.

As to how, exactly, Amazon is serving this slightly altered content to Google it's hard to say. Especially with gigantic websites, Google has been known to work out some agreement for "helpful cloaking" that really does benefit Google and its users. The infrastructure challenges faced by any mega site can be quite daunting and Google does bend a bit.

The bottom line here is that there is nothing truly deceptive about this, and nothing that artificially boosts rankings on important keywords. Rather, it is something helpful to all involved. And so it is one of those allowed cases where Google will accept being served something slightly different than the average browser gets.

They also watch this kind of thing closely for any attempted abuse. I know of one case where a big company tried cloaking that was aimed at improved keyword rankings, and Google dropped their product pages from the results until they cleaned it up and asked for reconsideration.