The Amazon.co.uk blog made an announcement earlier this month that it has launched Context Links, a new contextual ad system. It appears that they've been thinking about launching contextual ads for quite some time.
By adding a snippet of code to a website, Amazon will highlight phrases with associated products in their marketplace and let users navigate to the Amazon website to purchase the item. This appears to be available in both the US and the UK, and for now, it is in beta.
This is what it looks like:
What do you think of these ads?
Hat tip to gabs.
Forum discussion at Search Engine Roundtable Forums.