Just got the same question: i've got iMac with core i3 and MBP with core i7, is there any point to mine? I believe i need to mine currency on CPU, as GPUs are not powerful as CPU..And is it possible to mine using both of Macs via Wi-Fi?? 
Yes it is possible to mine via WiFi. But don't look into BTC or Scrypt mining. Look for CPU-only coins such as MemoryCoin, ByteCoin (BCN) etc