Hey everyone - I found the applescript mentioned and made some improvements. The script above doesn't handle titles longer than 255 characters (crashes Evernote) and doesn't preserve the note creation and modification dates. I've updated the script to take care of both issues - enjoy
tell application "Notes"
set theNotes to every note of the folder "Notes"
repeat with thisNote in theNotes
set myTitle to the name of thisNote
if length of myTitle is less than 255 then
set myShortTitle to myTitle
set myShortTitle to text 1 thru 254 of myTitle
set myText to the body of thisNote
set myCreateDate to the creation date of thisNote
set myUpdateDate to the modification date of thisNote
tell application "Evernote"
set theTransferredNote to create note with html myText ¬
title myShortTitle ¬
created myCreateDate ¬
set modification date of theTransferredNote to myUpdateDate