TeX Live 2012 release is near, so I think it is possibly a good time to sum it a bit, like it was done before with 2011. Feel free to add anything relevant in this community wiki.
What should we know about TeX Live 2012?
E.g. As a debian user I'm happy that wheezy (aka testing atm, freeze is planned on June 30) has the new TeX Live on board since May.
Best Answer
The TEX Live Guide for TeX Live 2012 has in section 9 “Release history” following information about the present version (page 39):
"Known issues in TeX Live 2012" adds: