Check theses guys out: http://www.hafele.com/us/products/folding-sliding-french-doors.asp

The doors pictured are generally referred to as 'stacking doors' or a 'stacking system'. The link provided above points to a site that does not seem to offer these. I've been looking for something like the ones pictured here, but have not found too many obvious options, either. http://www.nanawall.com/Static/stacking_doors.aspx seems to be one, though I have not yet contacted them myself.

Call your local glass company. If they do commercial storefront glass the can fabricate these. I dont think you will find any mass manufacturered units. It is not particularly difficult to make. Ensure there is no load on them tho.

We just purchased stacking doors from Sierra Pacific windows. Love the fact that they plant all the trees they use in their products. Not to the point we have installed yet. All there other windows that are in place are fabulous. And all our exterior doors and windows are LEED certified! Will add pics when complete. We also have a bifold or accordian type of doors from Sierra Pacific that we are using. Not in yet either. Lori