This sounds like a silly question but it really isn't. There are many, many, many word press blogs that are no longer going to be indexed according to Technorati due to vulnerabilities that old versions of word press posses.
It sounds like you are ok if you are using version 2.5 or have your blog hosted on there site, if you are hosting your own installation and are using an older version you should upgrade/patch your installation now to get your site back in the indexed listings of the top search engines.
They do this only to make your site more safe, and not compromise the security of your website so in a way they are doing you a favor
To read the whole article click here :
http://technorati.com/weblog/2008/04/424.html