Hi there, after months of searching for a tube map application for my 8700g I was sent an email by a company called VisualIT announcing their launch of maps for different BB models for London tube, NYC subway & Paris metro. Blackberry Software
They also confirmed to me that once installed, you don't need a wireless connection to view the map.
Great - at last!
(Also, for an introductory 25% discount use coupon code BBLPN25 at checkout.....)