Never seen the Threatcast tab ever!
Currently Using 3.13.121240.574 on Vista SP2.
Have double/triple ntuple times checked that Join Threatcast is on in settings.
Have been using CIS since launch, and never ever seen Threatcast.
Ofcourse, during install of CIS, i was NEVER connected to internet. I make it a point that I am not on net when my firewall is going to be replaced!.