Images in Google Alerts emails

This is not something I've seen - have you actually seen it? Images are not an option you can choose as far as I can see.

ive set up an alert for alfa romeo cars, and when i get the emails through from google, some of the blog link contain a small thumbnail image to the left in the email

At a guess, it sounds like a feature that depends on the query terms used for the alert - I can see why an image might be useful on alerts for that kind of term. It might be some kind of expansion of the Universal Search infrastructure or logic.

anyone more ideas on this