Originally Posted by: hdoranSuppose I play a harmonic on the 12th fret of the 1st string. What note is this technically?[/quote]
It is the note E, same pitch as the 12 fret note when fretted.
[QUOTE=hdoran]
If I were _on_ the actual 12th fret it would of course be an E. If I were on the 11th fret it would of course be Eb.

But, since I'm half-way between them, what is the correct technical way to refer to this harmonic note?

Actually, you are supposed to put your finger directly over the 12 fret to make the harmonic. And when you fret the note, it also blocks the string to make it ring from exactly the 12th fret to the bridge. So you aren't creating notes halfway between any fret. You only do that when you bend a note.

Also, harmonics are not always the same note as the fret they are found near. See this wiki page for a list of notes & why the harmonics create them.

http://en.wikipedia.org/wiki/Guitar_harmonics

Hope this helps!