  Single top quark production via the electroweak interaction was observed by
the D0 and CDF collaborations at the Tevatron proton-antiproton collider at
Fermilab. Multivariate analysis techniques are employed to extract the small
single top quark signal. The combined Tevatron cross section is
2.76^+0.58_-0.47 pb. This corresponds to a lower limit on the CKM matrix
element |Vtb| of 0.77. Also reported are measurements of the t-channel cross
section, the top quark polarization in single top quark events, and limits on
gluon-quark flavor-changing neutral currents and W' boson production.
