The current maintainer of gedit is Paolo Maggi <paolo (at) gnome.org>.
A mailing list [Archives]
is available to discuss developement of gedit itself, of plugins and for any question which regards gedit and its usage.
You may also join the #gedit channel on irc.gnome.org and have a chat with us.
gedit has a wiki page on the official GNOME wiki, where you can find useful information about current maintainance work and future developement plans.
gedit svn repository is hosted on svn.gnome.org.
You can get the code from GNOME svn with the following command:
svn co http://svn.gnome.org/svn/gedit/trunk gedit
./autogen.sh
make
make install
You can also browse the sources on-line using GNOME's ViewCVS service.
gedit bugs are tracked in GNOME's bugzilla. Here is a list of currently open issues.
You can submit patches to the gedit mailing list or in bugzilla.