Cairo is the new graphics library used by many GTK+ and GNOME projects. It's now a dependency of GTK+, and thus must be included in any uplift of GTK+.
Currently filed as bug 1858.
As an additional step, there's a library called "pangocairo" that should be considered as well.
Current status: a provisional import of the Cairo symbols has been done.
Integration of the cairo unit tests into desktop-test has been started.