Bewenched - 7:53 pm on Feb 8, 2010 (gmt 0)
I've noticed this too. Alot of forbiddens when I click the link from my google alerts.
They're possibly cloaking and showing content only to google. I think firefox has an add on so you can spoof that you are google and I'd bet the content shows up.
I almost wondered if it was one of my competitors that had paid someone to do this to devalue our pages. I have reported the ones I found, but who knows if that will make a difference.