After a series of leaks last week to the Chinese business press — including Xinhua, the Communist government’s official news agency — China Unicom (CHU) on Monday finally released some hard news about when and for how much it plans to begin selling Apple’s (AAPL) iPhone in China

But not much news.

“When” is in October — which could be as early as Thursday or as late as 33 days from now.

“How much” is something of a mystery. The official word is around 5,000 yuan ($732.20) — considerably higher than the prices that were being tossed around last week (those ranged from 1,999 to 2,999 yuan).

But the carrier did not specify how much iPhone (8 GB? 16 GB? 32 GB?) 5,000 yuan might buy.

And it offered some details — but not quite enough — about the service plans that will accompany those iPhones and reduce their initial sticker price.

There will be eight plans in all, ranging in price from 126 yuan ($18.50) to 886 ($130) yuan per month. They will include 450MB to 4GB of mobile data access, 120 to 880 SMS messages, 15 to 95 MMS messages, and between 320 to 3,000 minutes of talk time. A rate card would have been helpful.

It’s not clear what China Unicom hopes to gain by this mix of vagueness and specificity. Perhaps it’s to keep its competitors — China Mobile (CHL) and China Telecom (CHA) — off balance. Perhaps it’s to encourage customers to choose longer-term service plans when the final — and presumably heavily subsidized — iPhone prices are revealed.

Or perhaps they’ve learned a trick or two from Steve Jobs, a master of the art of managing the flow of information in order to keep his company in the headlines.

UPDATE: According to iPhonAsia.com’s Dan Butterfield, who has been following the story closely and can read Mandarin:

• The 5,000 yuan ($732) price is for a “no contract” iPhone (unclear whether that’s for 16 GB or 32 GB)
• Subsidies for customers who go “on contract” range from 893 yuan to 4,253 ($130.56 to $621.83).
• There is even a “free” 8GB iPhone 3G plan for customers who sign up for a two-year contract with the maximum messages, minutes and data plan.
• He describes 10 different service plans, ranging from the 66 yuan ($9.67) ultra-cheap student package to a high-end package that costs 886 yuan ($129.54) per month.

See here for Butterfield’s complete report.