As new methods to track errors develop, under what circumstances, if any, do you think journalists should be allowed to comment on corrections?

Journalists do this already, but it's vague: "Due to an editing error…" Errors hurt credibility, but, at least in my experience, not all errors are malicious or even the product of stupidity. Part of me would love to be able to say, "the CMS choked when we tried to save," or "we're shortstaffed today," or "there was miscommunication between the reporter and editor," or whatever.
We fix problems as soon as we see them. We try to improve.

My initial concerns: First, this may be looking for love in all the wrong places. Nobody may care whether we're blameworthy for a mistake. Publicizing will still, fairly or unfairly, hurt our credibility over time.

Second, journalists would need an incentive to actually explain errors more than "due to an editing error…," and who wants to admit a mistake?

Perhaps, though, news organizations' credibility should be punished for errors no matter whether the error was malicious. I would be open to that argument as well.

It wouldn't be hard, I think, to build in a way to attach corrections to stories, blog posts, etc, and publish a stream of those, linking back to the original work and making it easy for readers to find what's been changed. Part of it is cultural, as you said, but the tech side shouldn't be too hard.

Also, you should check out the way Slate handles corrections; they have a very cool system that shows readers exactly where the mistake occurred in a given article.