I don’t think there’s a plugin available for getting stuff from the camera (let alone other related functions) but you could always write one yourself.
In the end, if your program is mostly marking up stuff from the camera, it’s not clear how much value Unity would be adding to simply using XCode. OTOH if you’re mixing in a lot of 3d or whatever it might be a net win. (I doubt you’ll get a hardware abstraction layer across the iPhone and Android implementations of this functionality.)
Off Topic
I’m starting to wonder about the viability of Android as a platform. The way the cell phone companies are using Android it seems like we might start to see some fairly serious forking (e.g. Verizon is selling phones with Google locked out in favor of Bing… not really sure how Google is going to like this in the long run. Exactly how is selling someone an Android phone locked into Bing in Google’s strategic interest? Especially if it displaces an iPhone sale (since iPhone still defaults to Google).
Here’s a link to several videos with David Helgason discussing Unity’s partnership with Qualcomm and their Augmented Reality (AR) tech. I believe David mentions this is a post 3.0 release. But AR is getting serious!!!
Actually the App would make quite heavy usage of 3D elements so having Unity3D would definitely be a bonus… (besides cutting overall dvt times compared to SDK)