As a California architect I have looked into Autoclaved Aerated Concrete a few times over the years. Last time I checked it was manufactured in the US in, if I remember correctly, South Carolina and Florida and would pretty much be found only in those markets.
It was developed in Europe and began to be used fairly commonly there after WWW II. I have personally seen it used in Israel as infill for reinforced concrete post and beam construction. I think it is a good building material--but like all building materials/systems it will be most successfully used in an enviornment suited to its use and in the hands of skilled and experienced designers and builders.
Anytime you try an unfamiliar building system there is a fairly steep learning curve and a cost premium. I recommend that only those who can afford to be guinea pigs and are motivated with moving building technology forward build a home with an unfamiliar material. Over the years I have had the opportunity to try out or look at a number of different systems: insulated concrete forms, structural insulated panels, rammed earth, light straw/clay and cobb walls, straw bale construction and a some others. I did my house additions with Faswal blocks which are a commercial system of insulating concrete forms(blocks filled in place with rebar & concrete) made of wood chips, clays and portland cement also developed in post war Europe. I was fairly happy with it but as with all new materials there was learning curve and I would do some things differently the next time and, I'm sure, the time after that.
Generally the best candidate for unfamiliar construction methods are skilled contractors building their own house. If you get to the point of actually being in the position to build, I recommend you find an builder and architect in your area who has used whatever system you use on several successful projects in your area.
