I think it is f/4-5.6.
One big question though - is there any 1.4x or 2x converters that can be used with this lens and still allow it to retain the VR capabilities? If there is, then it'll be super -- imagine a 160-800 lens with 3-stops vibration reduction!!!
There is no mention of this in the Nikon press release (from their website). Nikon doesn't make any converters for AF lenses apart from the two AF-I converters, and I know those won't fit at all.
Anyway, this new VR function is only workable with the newer bodies (F5, F100, D1, F80).