I recently saw a long support arm that was mounted to the camera and to the lens foot. The whole thing fit on a wimberly. Does any one know what this beast is called and who makes it?

Was it this:

http://www.bhphotovideo.com/c/product/554349-REG/Manfrotto_by_Bogen_Imaging_359_359_Long_Lens_Support.html

Not sure if this is what you saw

The arm I saw had the camera mounted at one end, the lens foot mounted in the middle and a support for the end of the 500mm lens at the other end.

The arm connected everything seemingly quite solidly. The arm fit a wimberly head.

I used the Manfrotto long lens support with a SMC Pentax 500/4.5 for a while, and found that it wasn't very effective. The mechanical stiffness of the entire system was very high, and so vibrations weren't damped out very well at all. I think your best bet for a non-IS super tele is to keep the shutter speed high and/or use MLU. If you really want to minimize vibration (maximize sharpness) then a big bean bag is a great solution.

Really Right Stuff also has a rig to support the camera and the tripod foot of the lens collar. See the following link:

http://reallyrightstuff.com/rrs/Customkititems.asp?kc=KennanWardPkg&eq=

It obviously only supports the two locations, and you are looking for support at all three. To support all three locations, including the lens body near the front, you obviously need height adjustments and front to back adjustments at two of the three places to adapt to each individual lens and camera body. As far as I can see, RSS gear does not provide for a way to combine their hardware to do that.

I really like the concept of the RSS long lens support shown in a previous post that has the adjustable height wheels at the front, and holds the lens body at the tripod collar. That gives the best lever arm to form support for angular change of the lens, and it also still provides for un locking the lens collar and rotating the camera orientation. I do not like the exact execution, and would have prefered to not have the long bar sticking down at the front. The lens collar is by far the least rigid point when a big telephoto is mounted, and support near the front of the lens should help a lot. The RSS solution that has two wheels slightly to each side, and preloading the position just right, should put plenty of weight on the wheels, and thus support the lens for side ways movement as well as vertical movement.

Support of the camera body is the least important, because the lever arm is so short between the lens mount and the imagae sensor. It is the lens mount point that is the least stiff between the lens collar and the image sensor. Adding an extender or two does add problem points for flexing. Also, supporting the lens body makes it impossible to change the orientation of the camera. If you could have a rear set of wheels that could support the rear of the lens or the extender body just in front of the camera body, that would be a possible solution if you really need rear support. That would make the whole rig attached to the lens, and would allow for rotation. Perhaps RSS will come up with a solution like that some day.

Either of the two RSS support rigs can be mounted on a ball head or a gimbal head, so they each meet that part of your search. They also offer front to back movement to be able to get the balance perfect, which is helpful in handling the whole assembly. They have no need for an extra support rod to your tripod like the Manfrotto support rig, which seems totally impractical except for a very fixed setup. I would love to see other solutions to this issue posted if any can be found, because it is of interest to me also.