Last month we reported a November Google Image Search update. The thing is, many of those who watch the Google Image Search index are reporting a more real time indexing.
The WebmasterWorld thread I covered has updates. One update is from an image search hawk codenamed mssfldt. He said that Google is recently picking up his new added images within days. mssfldt said:
just as information: it seems that Google is now indexing new images fluently. Since Nov. 15 I see every day new images of my galleries in Google image search, with a delay of 3-4 days.
This is not as "fluent" or quick as the normal web index, which updates in minutes when the new Caffeine index launched, but it is much better than the monthly updates.
Forum discussion at WebmasterWorld.
Update: On Friday, December 10th, I heard back from Google. They confirmed a change where they have begun updating their image search index at a more rapid pace. I posted the confirmation at Search Engine Land. Here is the confirmation from Google:
We recently made some changes to increase the rate at which we update images in our index to improve the experience for our users and provide them with fresher images in both web and image search.