I still don’t see it considering your image shows an http connection not https, so I wouldn’t have though this would be an issue.

I have visited that blog and I don’t get any insecure content alert using firefox 6.0.2 image1.

On further investigation, I see why. NoScript is blocking a weird entry http : //s image2 (and of course facebook.net). Presumably that is the site trying to switch to https ?