Libgda is written in C, some bindings for other languages exist:
C++
Murray Cumming and the folks at Openismus are maintaining C++ bindings for Libgda and Libgnomedb.
Tarballs are at http://ftp.gnome.org/pub/gnome/sources/libgdamm and http://ftp.gnome.org/pub/gnome/sources/libgnomedbmm
Source code is also available in the Gnome SVN repository, or at http://svn.gnome.org/viewcvs/gnomemm/libgdamm and http://svn.gnome.org/viewcvs/gnomemm/libgnomedbmm for online browsing.
Python
PyGda (Gda bindings for Python) is part of the gnome-python-extras package. Libgnomedb does not have any python bindings.
GObject Introspection
Libgda creates GObjet introspection information at compile time, so it's possibile to directly use Libgda from any language which supports the GObject ontrospection technology, see https://live.gnome.org/GObjectIntrospection.
Vala
Vala bindings are now generated at compile time by Libgda.