We'd still venture to say that all signs are pointing toward an iPhone launch on China Unicom before too long, but one key element of the launch -- Unicom's upfront buy -- is now in question. A spokesman for China's third-largest carrier (which is an amazingly low rank considering they've got about as many subscribers as Verizon and AT&T combined) has denied earlier reports that they've stockpiled five million handsets in preparation for launch, saying that negotiations with Apple are still ongoing. We imagine that when you're dealing with a nine-figure subscriber count, any hardware n