I recently read this question:
which asks about something that has not, to my knowledge, happened in any Superman comics, but did happen on the TV show Smallville. It got me wondering how much, if any, of the events of Smallville are or were considered canonical within the larger DCU? Was it a separate version of Earth, or an alternate history, or did the show exist entirely outside of other DC material?
I'm particularly curious about the handful of episodes written by Geoff Johns which introduce or reference many other DC characters, including the JSA and the Legion of Super-Heroes. In addition, Chloe was very briefly written into Action Comics, though with a different background.
I also know that Smallville's plots are continuing via its own comic line, and was curious what DC's position on that series relative to The New 52 universe.