Since Yahoo rolled out a new Delete URL feature this week, a number of questions have come up on how exactly it works. I had time yesterday with some of the Yahoo Site Explorer team to gather answers. Thanks to Priyank Garg and Amit Kumar, who along with Tim Mayer, went through the inner workings.
It's probably most important to understand the difference between how pages have traditionally been kept out of Yahoo versus what Delete URL does. Traditionally, Yahoo is told not to spider pages at all using either a robots.txt file or a meta robots tag that uses the "noindex" setting. Here's some more about how those options work, versus the new Delete URL feature:
Article, Yahoo, Search Engine, Directory Submission, URL