As you may already know, there will be some essential changes with several Microsoft technologies in next version 2012 coming up.
According to those changes infrastructure design will also need to be adjusted. As well dynamic computing architectures and hardware selection in regards of storage.
The guys from NetApp have published a nice document for you to give you a feeling what needs to be taken into your conclusions about next infrastructure designs in regards of storage for your virtualization infrastrucuture and of course may be also for Exchange storage.
You should read this following this link