Glom is in GNOME's git. To check out the latest version:
git clone git://git.gnome.org/glom
It is also in jhbuild, which might make things easier for you.
See the Build Help page for more details.
Glom is built using gtkmm, the C++ wrapper for GTK+. It uses the Document/View model from Bakery, and the libxml++ C++ XML parser. It uses Python for custom field calculations. PostgreSQL databases are accessed via libgda.
The use of libgda means that Glom could theoretically support other database servers, but
- that is not particularly interesting or useful for the target users.
- that would require extra development and support.
- that is not a priority at this time compared to more user-visible features.
However, database server vendors (or others) could make this a priority by funding the work.
See the Development Plans page.