A few days ago, Technorati announced it was going to delist WordPress blogs it felt were spammy – not spammy themselves, you understand, but because of being hacked from outside.

Here’s what they are saying (emphasis mine):

we’re discontinuing processing crawls of blogs that exhibit common symptoms of being compromised

As to the exact criteria of a ‘compromised’ blog, it seems that invisible links to spam sites is the main thing.

The problem is that older versions before 2.3.3 are insecure, and so that version or 2.5 are the recommended versions to use. Although that’s part of it, hacked WordPress themes, a problem I mentioned a little while ago, could also be the cause.

So if Technocrati indexing is very important to you, check your theme over carefully (oh, why not check it over anyways!). Spam links will try their hardest to hide, so you need to view the source for anything with ‘http:’ in front.

In FireFox, it’s even easier – go to the Tools menu, then ‘Page Info’ That box has a tab for Links, which will list all the links on the current page. See anything you don’t like, and you could have a problem.

So if/when you have a chance, go through your blogs and make sure you’re good – and then consider a clean theme like ABTheme for your site, and upgrading to WordPress 2.3.3 or 2.5 ASAP!