I was also alerted by the excellent VMreference site to the existence of a PowerCLI reference card which is equivalent of the VM reference Card.
VI Internals has a pretty decent introduction to PowerCLI.
How my experience differed from all those online blogs and HowTos which explain how things just work. There are also some entries were I'm just trying to remember some "stuff" which seemed important or cool (in a minor way) at the time.