Thanks. Fascinating. Most browsers except IE seem to support it, allthough this xml entity was never added to HTML (just XHTML). So, strictly speaking, IE is correct. xowiki is updated in CVS head. See fishey for the change:
http://fisheye.openacs.org/browse/OpenACS/openacs-4/packages/xowiki/tcl/form-field-procs.tcl?r1=1.165&r2=1.166