Personally I'm more aligned to the NIST definitions re cloud (http://csrc.nist.gov/groups/SNS/cloud-computing/)- now these aren't perfect, but rather a common reference point. Sadly even those are being 'interpreted' conveniently by many now...
Couple of things I'm fairly clear about in my mind :-
- Virtualisation /= Dynamic Data Centre /= Cloud
- Virtualisation is often used currently for 'tin stacking' with existing provision & operations processes, nothing wrong with that but a short term capex and facilities opex benefit only.
- Cloud includes a wider set of topics relating to ownership, finance, roles/responsibilities, managed services, commodity and scale that are typically not address by the above points
- Shared Infrastructure /= Cloud
- 'pool' would be better term for shared infrstructure, and yes these are a good idea in enterprises (should be the default option for everything in the infrastructure stack)
Some of the questions I use as a litmus test for people telling me they are offering 'cloud services/technologies' is :-
- Are the actual purchase prices (not RRP etc, but actual buy prices) made available publicly for anybody to access?
- Are the prices the same for everybody (other than consumption based tiers)?
- Are the SLAs published publicly for anybody to access?
- Does the supplier publish a full TCO/ROI model for the customer to examine / adapt etc?
- What type of standards does this operate with / under?
- What is different between this and classic enterprise IT usage?
- Is the minimum duration of engagement hours, days, weeks, months or years?
- What is the 'startup latency' of the engagement?
- What are the metric elements for cost?
- What is the level of granularity of cost (consumption & change)?
- Do I need to meet/talk with a human in order to setup, purchase & use the technology or service?
- Is the technology or service fully controllable by a published API?