While checking the logs to see what's going on (yea, now it's documented - I do have one reader), I found out that when doing a Google Images search for "picasaweb" one of the pictures in the blog (the blog entry with the picture - here) appeared in the first search page:
Strangely enough, the picture is not hosted at picasaweb, although there is a copy of it in one of my albums.
Weird.