Yes, it is easy to separate the drives and revert them back to normal SSD and HD drives. It does require using a couple of Terminal commands at this time. Future upgrades may add that function to Disk Utility to make it easier. If you look at the threads on this forum for creating "Fusion" drives on older computers, you will see the Terminal commands used and there are additional commands to undo those operations.
You will have to restore all your data, so make sure you have a good backup before you start.
On the second page of this article is even shows the steps necessary to revert a Fusion drive back into the native drives:
http://arstechnica.com/apple/2012/1...ining-doc-ars-tears-open-apples-fusion-drive/
In my experimentation with "Fusion" on a Mac Mini and MacBook Pro I have built, broken, and re-built the Fusion drives several times for different configurations.
-howard