From Technorati blog:
Many blog publishers rely on ping relay service Ping-o-Matic to send blog notification updates including Technorati’s ping server. Ping-o-Matic has suffered brief outages in the past and the site is now completely offline. To ensure your blog notification updates are received by Technorati you should ping Technorati’s servers directly.
If you use WordPress and have not changed your ping settings your update notifications are currently not reaching any services, including Technorati and many online aggregators. To add Technorati’s ping server to your list of update services please follow the instructions on our WordPress ping configuration page.
Technorati has contributed hardware and some coding help to the Ping-o-Matic team in their efforts to provide a service to the blogging community. We will continue to work with Ping-o-Matic to make blog update notifications quick and simple but we recommend bloggers add Technorati to your update notification settings to ensure the message reaches its final destination.