Still might not be able to run squeeze center tho. Of course, if I can just be patient then in all likelihood we will see a Drobo II product by year's end with integrated eSata, FW800, Gig-E, etc. For the same $400 that the Drobo costs I could buy a pretty slick 6 or 8 bay ESATA external enclosure with hot plug drive bays.
Obviously there is a large cost hit (and a performance hit) to do things this way. The primary advantage (for me) of the Drobo as a storage pool is the upgradeability of the storage array without having to back things up, rebuild arrays, etc. Then plug Drobo into the ReadyNAS DIY box and (again theoretically) you could mount it up and use it with the NAS as ReadyNAS has support for USB storage. Take DROBO, build it as a virtual 16TB partition and then fill with disks then format NTFS fromt he Drobo dashboard. Supposedly FreeNAS now supports the NTFS-3G final version which means that it could, theoretically, support running the DROBO.