You can put a building on a site now, the tricky parts come in to mobility, GPS is not quite accurate enough to lock the buildings in, so you need some sort of feature recognition RE: the below research projects, there is also the issue of Occlusion, and not having the AR as just an additive layer above reality for building viz type work, 'peeking around a corner' and seeing lines of sight are not quite there now without a lot of extra work. (It can be done, but it gets tricky.) lots of interesting 'State of the union' thoughts by Michael Abrash from valve on his blog with respect to the current state and issues involved in bringing true AR to the masses.
there are a few interesting projects ongoing, these are more aimed at internal tracking though which I feel is the end-game, specifically if you look into SLAM and PTAMM, the , and the Kinect Fusion, Kintinuous etc... It's not quite there yet in terms of speed and usefulness and is really just in the research project and tech demo phases right now.
there are several distinct ways to get into AR, none of which are the end all be all yet. but its an interesting field to keep an eye on. here's an outline of some of my notes, mostly centered around unity and AR, and mostly from sometime last year with minor updates since then, so there may be some stuff out of date, but it doesn't seem too far gone as of yet: https://workflowy.com/shared/ea03a1fb-0be9-d28c-f664-f1fd3cdff76f/
On the whole it is still a nice effect and useful to help sell widgets, and also to help alleviate some of the pain of teaching people how to navigate around models, there are some more advanced things that can be done with it, but for the most part they don't scale up to the level of model detail and physical scale that arch is pushing right now, and are staying in the realm of museum exhibits and small tech demos.
I've done some AR projects and continue to experiment and play with it on any downtime. Its fun, I think it'll be useful.
I guess this stuff should be boiled down into posts at some point
Cheers,
Dave.