This one's based on pure speculation, with nothing official from Microsoft or Nokia, but after seeing the Nokia "Sea Ray" device's "accidental leak" last week by CEO Stephen Elop we could see NFC support in Mango if the device is truly identical to the Nokia N9.
We know Microsoft hasn't said anything about this at all, but it's been widely speculated for some time that Mango could enable this capability. Paul Thurrott over at Windows Phone Secrets points out the specifications of the N9 are:
A masterfully made, single-piece body that comes in multiple, scratch-resistant colors; a 3.9-inch AMOLED screen with curved Gorilla Glass; an 8 megapixel, wide-angle, 16:9 HD auto-focus camera with Carl Zeiss optics, superior low-light performance, and 720p HD video at 30 FPS capabilities; 1 GB of RAM; 16 or 64 GB of storage; a 1 GHz dual-core ARM processor; and up to 11 hours of talk time, 450 hours of standby time, and 50 hours of music playback time. Also included are turn-by-turn navigation and NFC capabilities.
It's likely that if they're identical devices that this does mean that Microsoft is probably testing out the NFC technology at the very least. Business Week reported back in March that the Redmond software company was working on a "version of its Windows Phone software that will let users buy merchandise with a flick of the handset at a checkout counter," citing two sources.
To confirm our suspicions even more, Business Week says that "Microsoft is likely to get support in its mobile payments effort from Nokia Oyj." They also point out that Microsoft holds 14 patents that reference NFC currently.
This rumor is up in the air but it makes sense for Microsoft to jump on the NFC bandwagon now, especially with the impending release of Google Wallet and Google's recent announcement to make it cross-platform compatible.