Thanks to Maria for alerting me to this:
All users should update to Bad Behavior 2.0.11 immediately to prevent being blocked from your own site.
Within the past two days users have found themselves blocked from their own sites while using recent versions of Bad Behavior. A third party blacklist which Bad Behavior queries recently began sending false positives for any IP address queried, causing everyone using Bad Behavior to be blocked. This issue is fixed in Bad Behavior 2.0.11.
I’ve now truly realised I’m directly responsible for 7 active blogs (and several others that don’t count as active). Updating one plugin across half a dozen blogs all at the same time is a bit of a pain: