In my testing I have used the Celerra simulator quite a bit. This helps me get familiar with the technology and features before trying anything in production. Now, it looks like they have released a new version that has the latest dedupe and iSCSI features.
The simulator can be downloaded from ftp://ftp.documentum.com/vmwarechampion/Virtual_Machine_Library/Celerra/5_6_43_18/. More information on the simulator is available at http://virtualgeek.typepad.com/virtual_geek/2009/04/new-celerra-vsa.html