As well as restoring the shopping tab to the main options bar on Google they have also added a show options link at the top of search results. It has some pretty cool features. You can choose to sift through videos, forums and reviews as well as time based results. There is also a pretty nifty search option called the wonder wheel.
Here’s a screenshot of it.
Once you’ve carried out a search you can choose to navigate through related search neighbourhoods using the wonder wheel. It’s quite handy in that one set of results will take you off to another web of results and so on until you find what you’re looking for. I could see users resorting to this after they’ve been through a few pages of traditional results. As usual with Google they’re not making a song and dance about it. It’s not advertised on their home page but just added quietly for users to discover themselves. The useful thing for SEO is that you can clearly identify which neighbourhoods of sites Google sees as related. Which can help when determining which sites to target for links. Thanks for that Google.