ARM is working on is new architecture version (ARM V8). This architecture will support 64bit. This is important for memory purpose. Because the maximum addressable memory with 32 bits is around 4GB. But also for the server market.
In my opinion this is especially for the server market, because the mobile market don’t currently need to address 8GB of RAM, and furthermore this can be handled via special instructions (like PAE on the 32 bits Intel processors) that allows to extend the addressable memory.
The server market is rapidly growing and the datacenters face to an important power dissipation (a big amount of their power consumption are due to power and cooling). So it is important to reduce the power dissipation of server, and especially processors.
This bring into the choice of low power devices like atom or ARM. This can be useful for example for storage servers where the processor performances are not so important. But also for computing because the low power consumption and dissipation allows to put more processors on the same rack size. This allows more density so more computation power on the same surface.