Today's blade servers are not directly related to virtualization but are often considered since the concept involves several kind of consolidation (physical, logical, partitioning, etc.). Quoting from SearchDataCenter.com:

Blade servers, which are deemed the next big thing in hardware, are also a big energy drain in an enterprise, according to a recent study that looks at the latest advances in server technology. The results of the study by TheInfoPro (TIP) Inc., a New York research firm, reveal that these new server technologies have not provided heating and cooling advantages. TIP recently released the second half of a server study it conducted in 2005. The research examined the concerns of 133 server professionals. ... Despite their intense heat production, the slim servers are indeed a priority for IT managers. According to TIP's survey, 62% of the respondents said they will spend more money on blade servers in the next year. Gill said blade vendors are realizing that excess power is a problem in terms of energy efficiency, and there is an initiative among them to create blades that are more energy-efficient. A number of groups have suggested that vendors should develop a standard for measuring energy efficiency and then develop technology accordingly. He also noted that virtualization technology would alleviate some problems with power efficiency and consolidation...

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