Just updated my aTV3 and 2 x aTV2 to 6.1.1 update released a short time ago and can confirm that PlexConnect works without any problems - in fact the aTV and PlexConnect seem to be working fast - certainly appears to be a performance improvement.
Can't see any other changes showing up with the new firmware update - i'm assuming this update is to address heartbleed issues and maybe some other bug fixes.