Depends to what level, if the thing does say 1000MH/s it's not bad as long as your not paying for electricity, if you were at a company that has a few of them it's even better, OS X I've found is very easy to run a miner on and find it to be stable.
There is no way in hell it would ever reach that kind of performance...
It is stated these will feature nVidia graphics, which are not known for good hashing performance anyway even with CUDA.
Mac is probably one of the worst things you could use for mining purposes. At current difficulties you need dedicated rigs to even make it worth your while.