GCC 4.6.3 was released on 1 March 2012. Due to recent work on the gnat-aux package, it was relatively easy to update the pkgsrc version of gnat-aux to version 20120301 which syncs with GCC Release 4.6.3. It has already been tested and committed to the pkgsrc CVS trunk.
The same can't be said for the FreeBSD version. The port updated okay, and would work fine on FreeBSD 8.x and below, but it's failing FreeBSD 9.0 ACATS testsuite. It turns out that version 4.6.2 was failing as well. Specifically 23 tasking tests are failing with "Fatal error 'thread exits with resources held!'". This is caused by an update to the thread library that detects this sort of thing and FreeBSD 9.0 is the first version to use the updated library.
I will try to modify GNAT to free the thread's resources so that tasking for FreeBSD will work. Also, the gnatdroid port will use part of the gnat-aux makefiles and patches so that it will automatically update when gnat-aux updates. It is still at gcc version 4.6.1, but an update for that port will follow shortly after gnat-aux is fixed.