[Greenbuilding] framing for raised vegetable beds

[candtcampbell at juno.com]

Many months ago I asked the list for recommendations to construct raised vegetable garden beds. I think someone recommended some sort of autoclaved aerated concrete product that was not yet available in my area (Georgia). I'm looking for something non-toxic that will last indefinitely in ground contact. What is available now? Does anyone have experience with the product described at concretelumber.com?

Tim