Update: I've added user specified encoding. When you click Settings, you can indicate what encoding the POI file should get (default from Google is UTF-8). If characters cannot be recognized, they are replaced by question marks (?).
For Russian, you'd usually choose Windows-1251 (cp1251), for most European languages, you'd choose ISO-8859-1.
Make sure that MapThis also understands what these characters mean. See http://www.dcemu.co.uk/vbulletin/showthread.php?t=70091 for this.