We recently noticed that for some products, Google has inserted a dropdown menu that allows users to switch more easily among product variants. The product pages for the individual variant items still exist and appear in search results, so this is really just a linking of existing related content. For example if you search for “canon powershot sd1300” you should see product pages for all five colour variants but if you click into any one of those, you’ll see a menu set to the colour on which you clicked.
This seems to be a moderately useful function for this product type but the real question is how will this extend out to apparel, shoes, accessories, etc. where colour and size variants can reach into the dozens or even hundreds. Product pages don’t exist in those categories at this point but it seems likely Google will eventually move in that direction for those product types in the interest of improving the user experience and making it more like what a consumer would see on a retailer’s website.