Tamron announcement November 7, 2103
As previously mentioned, Tamron will be announcing a new lens on November 7, 2013.
Apparently the new lens will be a replacement for the current 200-500 f/5-6.3 lens. The new lens will have an increased zoom range (150-500?) and vibration correction (Tamron's IS).
This is going to be a development announcement, we won't see the lens until well into 2014. Pricing will not be immediately announced either.