Danny Sullivan:

Eight years ago, Google viewed paid inclusion in general as some type of evil the company should avoid and in particular something that could cause shopping search to have poor relevancy or be biased.

What happened to cause such a change?

Oh, me, me, me! Google changed the definition of paid inclusion. Clever.

I don’t really care about this because my ‘shopping search engine’ is Amazon.com, but this is just another change (among many) from the Google that we all used to know and love.