Thinking along the lines of using TW's image pop-up component with a swf that contains a Google Map extract, then link this to a hotspot from within any pano in a tour.

How to achieve this?

By using the free AFComponents Gmap component (a Flash plug-in).

Using Flash and this plug-in, you could successfully created a "Google Map swf" and can insert this into the image holder in TW.
This means you can control the size of the map and do not have to launch any more browser windows, or link to any html iframes; It is all contained within a TW tour, very neat!

Now that there is a Google Flash API released, maybe there will be more options like this one in the near future. For more details about applying google map in virtual tour, refer to a thread in Easypano Forum.