Microsoft is stepping up its trade-in promotion pace as of late, seemingly to try to stimulate demand for its Windows Phones and Surface tablets.

The latest new promotion, offered via the Microsoft Stores, is an iPhone trade-in. Kicking off today, September 27, the new promotion allow user to bring in their "gently used" iPhone 4S or iPhone 5 for a minimum $200 gift card which can be applied to any products for sale in the Microsoft brick-and-mortar stores. The promotion runs through November 3, 2013.

Earlier this month, Microsoft launched a similar iPad trade-in promotion via the Microsoft Stores . The company also launched a Corporate Buyback Program allowing users to earn up to $350 to use to buy Surfaces and Windows Phones for trading in iPads, iPhones and other competitive devices .

I have no idea how successful these promotions are or are likely to be. But Microsoft officials seem to be continuing with them as we approach the start of the holiday season.