Virtualization

Not a magic bullet

Can multiple the number "machines"
At scale not as efficient as dedicated machine... thrash your level 2 cache, etc
You still have to admin the machines

Good Things

dev -> QA -> production can be the same image
great container... lets you pre-stage and do large scale atomic switches and rollbacks
useful for HA with VM motion
provides a good layer of abstraction... hardware changes, machine "image" stays the same
great if you have servers you want to version seperately, but they won't consume resources on a single machine

Technologies