Presumably this is a support for holding the "3 jeux de plaquettes pour les différents cafés".

Whether it is actually a "sales" device or more of a "display" device I don't know, but I would opt for the latter.

In any case, just "triple holder" probably suffices.

I'll ask George next time I see him.

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Note added at 2 hrs (2008-05-09 13:45:12 GMT)
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Can't help wondering if it's not a franglais duplicate repeat of a redundancy for "POS (point of sale) de vente".

Nowadays my morning fix at Starbucks has become a tortured, inferiority-complex building journey. Now I pull the aging Lexus into a parking lot filled with Dodge Rams and stand in line behind real men. Their steel toed Redwings dwarf my flimsy Italian mocs. My pale limbs and doughy fingers appear useless compared their beefy, sun-bronzed guns with calloused mitts wrapped around Vente triple shot lattes delivered by smiling barista babes. The same baristas simply smirk at my corporate hairdo as they indifferently hand me my Grande double shot, eager to serve the real heroes.
http://www.capitalstool.com/forums/index.php?showtopic=3762

OK, Starbucker, but if I buy you a vente triple shot latte will you tell me when I swing through your city on Hazel? Or perhaps you are more the Americano type....
http://managementcraft.typepad.com/management_craft/2007/02/...

I presume it's Italian but I don't know what it means!

Look up 'Starbucks vente' -lots of hits.

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Note added at 1 hr (2008-05-09 12:52:06 GMT)
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The key, though, is moderation, which Clemens says translates into
three to five cups a day. We're talking standard cup here, about eight
fluid ounces, not a Starbucks' vente cup, which is 20.
http://www.health-forums.com/alt-support-arthritis/weekly-he...

vente refers to the fact that it contains 20 fluid ounces. The triple must refer to the milk or cream or such like.

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Note added at 5 hrs (2008-05-09 15:57:44 GMT)
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Several hours later.... with the old brain ticking over

I think this is nothing to do with my previous answer but it simply means

pose de comptoir de vente - with the bit the customers see with an expensive finish and the two parts the vendor sees with a much cheaper finish - so basically the translation would "fitting of sales counter" or some such expression.