Is free virtualization software like free puppies?

Over at my Linked-in group, virtualizaitionfocus -- which is the companion social net site to virtualizationfocus.com -- I've been having a discussion of how free are the free versions of virtualization software. Ace tech guru David Strom has weighed in the differences between VMware's ESXi (the freebie) and ESX (the feebie). I'm thinking free isn't all that free for any of the free offerings from Citrix, Virtual Iron, etc. I'm looking for your experiences. 

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