[wanorris]

As common as virtualization is becoming , that could be a good solution as long as they can keep a ceiling on the memory cost -- true virtualization can be really expensive, memory-wise.

On the other hand, if they're simply talking about a conventional compatibility box, this is less of a worry -- Windows has been doing variations of this for years for backwards compatibility -- since long before OS X.

This article skips past all the technical details, but the smartest solution might be to make the new API purely managed (i.e. .Net), and run all unmanaged apps in a compatibility box. This is great for stability, and it ends the days where you have to dig down into C or C++ and mess around with window handles to use certain OS features that aren't available otherwise.