Here's an official statement from the Blogger Buzz blog:
We want to offer our sincerest apologies to affected bloggers and their readers. We’ve tracked down the problem to a bug in our data processing code that locked blogs even when our algorithms concluded they were not spam. We are adding additional monitoring and process checks to ensure that bugs of this magnitude are caught before they can affect your data.Many bloggers who were affected by this issue were justifiably inflamed by yesterday's incident, and I sincerely hope this apology will go some way to quell dissent against this otherwise great blogging platform.
At Blogger, we strongly believe that you own and should control your posts and other data. We understand that you trust us to store and serve your blog, and incidents like this one are a betrayal of that trust.