Running:
FreeBSD localhost 10.1-STABLE FreeBSD 10.1-STABLE #1392  r274646M/274647:1001502: Tue Nov 18 04:51:06 PST 2014     root@g1-253.catwhisker.org:/common/S1/obj/usr/src/sys/CANARY  i386

Have x11/nvidia-driver installed and in use (on my laptop):
COMMENT=        NVidia graphics card binary drivers for hardware OpenGL renderinlocalhost(10.1-S)[5] pkg info x11/nvidia-driver
nvidia-driver-340.46
Name           : nvidia-driver
Version        : 340.46
Installed on   : Tue Nov 18 06:00:05 PST 2014
Origin         : x11/nvidia-driver
Architecture   : freebsd:11:x86:32
Prefix         : /usr/local
Categories     : x11 kld
Licenses       : NVIDIA
Maintainer     : danfe@FreeBSD.org
WWW            : http://www.nvidia.com/object/unix.html
Comment        : NVidia graphics card binary drivers for hardware OpenGL rendering
Options        :
        ACPI_PM        : on
        DOCS           : on
        LINUX          : off
        PAE            : off
        WBINVD         : off
Shared Libs required:
        libXext.so.6
        libX11.so.6
Shared Libs provided:
        nvidia_drv.so
        nvidia.ko
        libvdpau_nvidia.so.1
        libnvidia-glsi.so.1
        libnvidia-glcore.so.1
        libnvidia-eglcore.so.1
        libnvidia-cfg.so.1
        libglx.so.1
        libGLESv2.so.2
        libGLESv1_CM.so.1
        libGL.so.1
        libEGL.so.1
Flat size      : 98.0MiB
Description    :
These are the official NVidia binary drivers for hardware OpenGL rendering
in X11, using the GLX extensions.

WWW: http://www.nvidia.com/object/unix.html


And it's working, but I happened to note:

Nov 18 09:59:20 localhost kernel: REDZONE: Buffer overflow detected. 16 bytes corrupted after 0xd2375200 (256 bytes allocated).
Nov 18 09:59:20 localhost kernel: Allocation backtrace:
Nov 18 09:59:20 localhost kernel: #0 0xc0d8b3ba at redzone_setup+0xda
Nov 18 09:59:20 localhost kernel: #1 0xc0ab9bd4 at malloc+0x244
Nov 18 09:59:20 localhost kernel: #2 0xc1d2f9d1 at os_alloc_mem+0x21
Nov 18 09:59:20 localhost kernel: #3 0xc1d1cc1e at _nv013362rm+0x12
Nov 18 09:59:20 localhost kernel: Free backtrace:
Nov 18 09:59:20 localhost kernel: #0 0xc0d8b790 at redzone_check+0x310
Nov 18 09:59:20 localhost kernel: #1 0xc0ab9c18 at free+0x38
Nov 18 09:59:20 localhost kernel: #2 0xc1d2f9f9 at os_free_mem+0x19
Nov 18 09:59:20 localhost kernel: #3 0xc195bcc7 at _nv004407rm+0x19d7

which looks a fair bit as if nvidia.ko is doing something ... inadvisable.

I realize that our (FreeBSD.org) "leverage" is .... minimal.  But I'm pretty sure that failing to report the issue won't help, either.