Where Can I Get "gio-2.0.so" ?

To install 'cheese' I need that file with a version number >= 2.45.8, but the one I get from /usr/ports/devel/glib/devel20 is too old (2.44.1).
devel/glib20 is at version 2.46.1 in both the head and quarterly branch of the ports tree. Your ports tree seems to be at least a year old based on the glib version you seem to have. What FreeBSD release are you on?

Are you trying to install the port multimedia/cheese or compile cheese directly from sources?