All material nodes within Maya contain
a "normalCamera" attribute. This is infact the attribute
to which a bump node will be connected. The bump node can either
be of type MFn::kBump or MFn::kBump3d. Where games are concerned,
a 2d bump map is probably the only thing you'll need to worry
The file that is used as the bump
map image itself is used as an input to the bump map node. This
is a simple greyscale image that defines the bump. The bump node
essentially converts this to a tangent space vector that can be
used by the surface shader.
Any image you retrieve as the bump
map, should be run through a conversion process to encode the
normals into the texture.