see: http://developer.atlassian.com/jira/browse/CLMVN-47
This could be set in a meta tag, directly in the HTML:
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
Alternatively, since the HTML reports are actually XHTML we could use:
<?xml version="1.0" encoding="ISO-8859-1"?>
at the top of each file.