I think it should be flat and painted like the top as well.

I'd make the cabinets and the divider look like all one piece. That would mean baseboard goes along side of the cabinet and around the foot of the divider; also, beadboard on both surfaces. I'd also, if it were possible, trim the divider flush with the cabinet side so the beadboard would have no jog in it and you wouldn't need corner molding between the cabinets and the divider.

The exact same material, cut the same dimensions (width) should simply continue down the divider. It will hide the actual corners of the divider, making the corner trim unnecessary. If there is much distance from the leading edge of the divider and the cabinets, again using the same material as the top of the divider, make a box that wraps around the sides, using mitered corners so it appears to be one solid support post. It may take a bit more work...but you don't want to let a bit harder work stand between this looking cheap and expensive, do you? It's a big deal because it will become the focal point because it happens to be on that end that is exposed to the room.

this is what I meant:

The divider end will be flat on all sides. The top will remain as is shown. The entire divider is to be painted gloss white. Thanks to everyone for your help.

Jennifer, I was going your way.

Bill, can we see the finished product? I always like to see the 'after' picture.

I am currently in almost the place your at, and this is what I ended doing. I haven't trimmed it all out yet though.

As soon as it is finished I'll post a photo.