A couple weeks ago I noticed that links in the Yahoo! directory have changed in format. Prior to this, links in the Yahoo! directory were standard HTML links straight to the target site. Now, the links are passed through a stats script.
Since it just happened recently, we don't have any data on what this will do to Google's ability to use Yahoo! as a resource for citations (PageRank).
We're still seeing backward links from Yahoo!, but it's possible that Yahoo! backward links will no longer count after this next update. I.e., the backward links we're seeing now are old data (older than a couple weeks at any rate).
It's also possible that Google is working with Yahoo! on a way to index the directory without sending out a standard spider, perhaps by getting its own copy of the Yahoo! directory to spider.
In Brin's and Page's original paper, "The Anatomy of a Large-Scale Hypertextual Web Search Engine," there is specific reference to Yahoo! as an excellent source of citations. I'm wondering if that's about to end.
If Google were unable to index the Yahoo! directory, that would alter the PR landscape quite a bit.
There's plenty of room for speculation and conjecture here. Let's see what we can discover.
Has anyone heard from Yahoo! or Google on this issue. My inquiries have not been answered.