On Jan 17th at 20:52 UTC there was a network outage that caused the Akismet.com DNS servers to be unavailable for 12 minutes. The problem has since been fixed, and everything is back to normal now.
This means that for some blogs, there was a brief window where the Akismet API servers were unavailable. If you’re running version 2.5 or later of the Akismet plugin, any spam or comments during that window were held in the moderation queue, then re-checked a few minutes later.
We apologise for the inconvenience. If you’re running WordPress 3.0+ and haven’t already upgraded to version 2.5 of the Akismet plugin, we’d like to remind you to update, since the new plugin includes features specifically designed to recover from a situation where your blog can’t reach the Akismet API servers.
If you’re ever in doubt, you can see independent third-party availability monitoring of the Akismet API servers here.
Akismet 
My comment is unrelated to your post – sorry! I just want to send out my thanks for the Akismet service and cannot find a place to put my Kudos.
I just finished deleting 130 spam comments attached to one of my posts. All disgusting, and all blocked by Akismet without my sensitive readers ever having to know about it. (wink) This is a fabulous service requiring no effort from me and providing a great benefit.
Thank you, thank you.
Happy we can help 🙂