Yahoo Site Explorer Beta, rather like Google Sitemaps, is meant to allow Net users to:
"explore all the web pages indexed by Yahoo! Search. View the most popular pages from any site, dive into a comprehensive site map, and find pages that link to that site or any page."
For bloggers, again as with Google Sitemaps, adding your site to Yahoo Site Explorer should hopefully get your blog better indexed by Yahoo, give you more info about how Yahoo indexes your blog (including links to your blog as detected by Yahoo - see this Site Explorer search on my blog URL for an example), and will enable you to ping Yahoo, i.e. get Yahoo to come and reindex your blog whenever you've added a new post. Here's the Yahoo help pages on Site Explorer.
When you've added your site (here's an alternative method to submit your site or feed to Yahoo - either way you have to have a Yahoo ID but you'll be given the opportunity to create one), and you login to Site Explorer, you don't get much except the ability to "manage" your sites:
and "Manage" so far really only offers a way to submit your site feed to Yahoo:
There's also a tab about "authenticating" your site. And there's the rub. As with Google Sitemaps (whose equivalent of "authenticate" is "verify"), authenticating your site with Yahoo is A Good Thing if you want more info about how Yahoo crawls your blog, because:
"Once you authenticate your site, you will have the following additional information about your site at your fingertips
* The status of your submitted feeds, when they were last processed and when you submitted it, or last pinged us for a feed
* Additional information for the pages in your site, including the language as detected by us, and the last time we crawled the page
* List of subdomains from your site in the index (if your site was a host such as yahoo.com)"
However, as it was once upon a time with Google Sitemaps (though they've since fixed that), the only way you can authenticate a site with Yahoo is by uploading a special file to your blog server - and those of us bloggers using Blogger on its free Blogspot servers just can't do that.
Now I get at least 95% if not more of my visitors from Google but I do get a few from Yahoo occasionally, so I'd like my blog to be as fully indexed and up to date on Yahoo as possible. Therefore I want to be able to authenticate my blog with Yahoo by some means other than uploading a file (e.g. by adding a special meta tag in my template). I've requested that, and I'm clearly not the only person who's concerned about how you authenticate a Blogger blog - see e.g. this.
The more people who ask Yahoo for an alternative authentication method, the more likely it is they'll allow it, so I hope lots of people will consider posting on the Site Explorer forum or giving feedback to Yahoo on this (login to Site Explorer then click the Feedback link).
UPDATE: Yahoo have finally added meta tag authentication, see this post.
(Also, Site Explorer seems to consistently crash Internet Explorer on my system at least, but not Firefox. Anyone else had that problem?)