Yes, it is now global_vars.map_name. All singletons exposed from C++ and objects that are the one and only instance of a class were renamed from CamelCaps to lower_with_underscores a few weeks ago.
If you look at the link Ayuto provided, you should notice that anything that is defined by
.add_property is a retrievable property value. Anything defined by
.def_readwrite is a readable/writable attribute. And, anything defined by
.def is a member function.
Also, anything that has
NOT_IMPLEMENTED in front of it, is defined on an engine-by-engine basis.
One more thing, while the wiki is still a work in progress, the core package has been documented for some time:
http://wiki.sourcepython.com/index.php/core
http://wiki.sourcepython.com/index.php/core#global_vars
http://wiki.sourcepython.com/index.php/core#map_name