Has coreaudiod been fixed in Lion yet?
Nope it hasn't. I'm still having problems in Logic because of it. I plug in a headphone cable, unplug it, and suddenly the computer doesn't have sound. Try killall /usr/sbin/coreaudiod then relaunch it, I get this:

[...] Error: FIXME: IOUnserialize has detected a string that is not valid UTF-8, "?-8?????-8????PDa????@Da????0??????Ԕ?????&lt;????????c".
Aug 14 01:56:48 Benjamins-MacBook-Pro.local coreaudiod[7392] Error: FIXME: IOUnserialize has detected a string that is not valid UTF-8, "?-8?????-8????PDa????@Da????0??????Ԕ?????????????c".
Aug 14 01:56:48 Benjamins-MacBook-Pro.local coreaudiod[7392] Error: FIXME: IOUnserialize has detected a string that is not valid UTF-8, "??c".
Aug 14 01:56:48 Benjamins-MacBook-Pro.local coreaudiod[7392] Error: FIXME: IOUnserialize has detected a string that is not valid UTF-8, "??c".
2012-08-14 01:56:48.994 coreaudiod[7392:707] Exiting due to uncaught exception in main


Apparently I've got some low level bug in my operating system or coreaudiod just wasn't compiled right.