Certain mystery cases have been revealed in China that bear resemblance to the iPad 2. AppleInsider and MIC Gadget have gained access to iPad 2 shells that display nearly identical cut-outs. These shells have displayed a rear-facing camera, an SD card slot, and perhaps even a Mini DisplayPort receptacle. The first two features have been confirmed; however the third is still dubious.
However judging by the size of the hole, a Mini DisplayPort seems pretty much a likely inclusion Apple will make for the sake of offering choice. This considering the fact that you might still have to send your video streams over an untethered AirPlay connection.