Google Image Update - when was the last, when is the next?

As a landscape photographer in Sligo/Ireland, I have downsized images
of all my works on the net (http://franklludwig.com/photographs.html),
and most of them can be found on Google Image Search.
However, I have added a new page in July 2006
(http://franklludwig.com/yeatscountry.html) with which I hope to
attract a few more customers who are looking for locations of Yeats'
poems.

The new page can be found on the Google Web Search all right, but it
still isn't indexed in the image search. Yet, pages and images that I
have added in June 2006 (one month before the Yeats page) have been
added to the image search results in October 2006.

Has there been a Google Image Search update since July which simply
missed the page? And if so, will it be able to find it the next time?

And does anybody know when the next update is going to take place?

(And yes, I have added the page to my sitemap, and I have enabled
Enhanced Image Search.)

 

All right, someone wrote to me and told me that Google Image Search is
constantly updating, just like the usual Web Search.
Fair enough, but that still doesn't explain why the page I created in
July 2006 was not included when my other images were updated three
months later.

Any suggestions?