If you're logged into Piwik and you open the world map widget it shows up fine. If you log out and reload the widget the following error is thrown:
"Fatal error: Cannot use string offset as an array in /xyz/piwik/plugins/UserCountryMap/Controller.php on line 52"
Request: /piwik/index.php?module=Widgetize&action=iframe&moduleToWidgetize=UserCountryMap&actionToWidgetize=worldMap&idSite=1&period=day&date=2011-04-04&disableLink=1
(In [4336]) Fixes #2264