The idea would make sense for Apple, in a certain way. ARM is a very important chip maker and Apple is buying most of those chips from them. That is because most of Apple’s devices (including the iPhone) use ARM CPUs to work.
If it bough ARM, Apple would have its own chip manufacturing company, allowing Steve Jobs’ boys to develop new products more efficiently and to manufacture them in a more cost-efficient way.
There are also voices that say the move would not make sense for Apple at this particular moment. The reason is that ARM would be quite costly to buy right now. They make chips for a lot of smart phones and they’re doing very well, so the price would be quite high.
Even so, the price that is rumored on the market is $8 billion.
What will happen in the near future remains to be seen, but Apple could also decide to become a shareholder in ARM.