Julia has support for Unicode operators. Most editor plugins for Julia allow you to enter the characters using (La)Tex syntax, so it’s quite common to see.
Unicode support doesn't really seem that uncommon, in the grand scheme. Rosetta Code's wiki has a page for languages that support Unicode variable names[0] and some of them were surprising to me (e.g. AppleScript).
Of course, supporting Unicode variable names doesn't mean a language supports Unicode anywhere, but it's a starting point for historical research at least.
