[Steely Tom]

Many metal oxides are insulators.

Hence, "Metal-Oxide-Semiconductor" transistor, or MOSFET. First proposed in 1925, according to Wikipedia. The computer you're reading this on wouldn't be possible without them.

[decimon]

Many metal oxides are insulators.

Looks like these metals are conductors.

[Eragon]

For terminologies sake...
yes metal-oxides are generally insulators. In layman’s terms we call them ceramics. Ceramics can be made semiconducting, it’s all about the bonding and the resulting band gap.

The insulating layer that they are talking about is not conducting the electrons, rather they are traveling through it via tunneling which while sounding similar is utilizes quite a different effect.

[Condor51]

*** The computer you're reading this on wouldn't be possible without them. ***

That.
And Bill Gates' parents 'getting jiggly' in Jan of 1954
;-)