I was just thinking the same thing? I used to be running one of the archive hacks under v2.8 and I was getting bombarded by spiders all day long in my archive area. Now with v3 Ive been getting nada? I think it has to do with "index.php" being in the url. I have seen other forums running v3 without the "index.php" in their archive URL.
Anyone have a answer to this one?
Here is a site running under v3 without the index.php in their archive URL
http://forums.asiansinc.com/archive/f-72.html