Is the VID range the maximum vcore for overclocking?
NO. The maximum VID shown on the Intel Datasheets is not the maximum vcore for overclocking. For each series of processors there is a chart of Absolute Maximums and Minimums, which are the exactly as they sound: the maximum and minimum voltages you can safely run without hurting the CPU. However, caution should be taken at exactly these voltages as Intel implies that a 1.55v maximum means that 1.55v is not okay, but 1.54v would be okay. The VID range is simply the range of VID that Intel is willing to sell.
For 65nm Core 2 Series, the Absolute Max is 1.55v.
For 45nm Core 2 Series, the Absolute Max is 1.45v
For 45nm Core i7 900/800 and Core i5 700 Series, the absolute max is 1.55v
For 32nm Core i5 600 and Core i3 500 Series, the absolute max is 1.40v
The logic argument to the VID range being the maximum vcore allowed is simply the question of what does the Absolute Maximum mean if the VID range is the Absolute Maximum. This argument is also proven in the Intel Datasheets for the i7 900 Series, where they show the pin configuration for up to 1.60v, when the absolute maximum voltage is 1.55v. The VID is simply a pin configuration in order for the CPU to request the proper amount of power and has nothing to do with maximum voltages.