> You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:

> [...]

> c) You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.

This is a requirement which is common to many GPL-like licenses, and one which some developers object to (the later requirements for use over the network notwithstanding).

That said, I don't believe the above terms would apply to the hypothetical Google Maps example above, as the license's requirements for making the software controllable over a network seem to be significantly less restrictive:

> Notwithstanding any other provision of this License, if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network (if your version supports such interaction) an opportunity to receive the Corresponding Source of your version by providing access to the Corresponding Source from a network server at no charge, through some standard or customary means of facilitating copying of software.

In that situation, the question of what constitutes a "derivative work" might come into play.

Disclaimer: I'm not a lawyer and this isn't legal advise, just my own interpretation based on my reading of the license.