I find this very interesting. A recent article I wrote on SQL 2008 Clusters here
did become a bit of a VMware discussion, the point I was (trying :pinch
to make was that sometimes, Virtualisation is a difficult sell, even to the point where this would sacrifice a "perfect" solution in favour of a "workable" solution. Banging a bit of a different drum.
I your article is a great eye opener and good points for consideration when implementing large or small Virtualisation infrastructures. Virtualisation as a technology is there, its mature and it works. But Virtualisation has wider implications as a concept to an organisation. The impact into Operations (backups as you mention,) needs to be understood and as you also mention, collaboration and buy in from the right teams.
Great article. Thanks for sharing.