ATI demonstrated gpu physics using havoc fx years ago now and it never really materialised.
Also, just because a game uses havoc, does not mean they will use gpu accelerated physics, lots of games use software physx without bnothering with the hardware side.
True, the point here is that AMD will show GPU acceleration for havoc physics this time.
There is much more that the havok engine is capable than is currently used in games due to CPU utilization limitation.
Look at for example the physx engine, try enabling physx on Mirrors Edge with out a PPU so you are doing all of the calculation on the CPU and your FPS will go down to 14 Framesper second.
Why it didnt materalise before is because Intel purchased Havok, and they've been negotiating the licensing with AMD ever since. If you google around you will find a few articles that talk about it.