Saw this announced on the wxWidgets announcement list.

http://www.kirix.com/labs/wxwebconne...ebconnect.html

wxWebConnect is a Web Browser Control library for wxWidgets that enables developers to quickly integrate advanced web browser capabilities into their own applications.

To achieve these capabilities, wxWebConnect wraps functionality exposed by the Mozilla Foundation's Gecko engine (XULRunner) into a set of user-friendly classes, allowing developers to easily embed browser controls, search web content, print web pages, interact with the DOM, implement custom content handling for different MIME types, issue POST calls using the current browser state, and perform other advanced operations.
So if you're writing a C++ app (a game?) that needs an integrated web browser, you can embed the core of Firefox in it.