I just noticed this today on two different blogs I have, both upgraded to 2.2.3. I had not noticed it prior.
Where I noticed it was in the tagline for the blog, where, in the case of my son's blog, had a tagline like so:
"some text here, it's great"
so some double-quoted text, with an apostrophe in it, ended up like so:
\"some text here, it\'s great\"
which as you might imagine, looks rather odd in the tagline.
I've noticed it's being escaped with slashes even when I remove the slashes from the Tagline box in Options, it reappears there, and is saved and displayed this way again.
I have no idea offhand if this is happening elsewhere in WordPress/in my blog, but if it is, I'd love to know, so I can roll things back or at least know to keep an eye out.
I'm obviously keen on some guidance or fix for the problem in the first place, too. :)