I've just installed this. I've not had chance to play around with the settings yet as the main reason for installing it was to make sure it would work with the new version of my split user plugin. That seems fine but I did notice that this Mod doesn't currently comply to XHTML Validation (because your code isn't within a <li> element). It's not exactly a major issue but changing the last line of your plugin to the following should make it comply.
PHP Code:
$activeusers = '<li><b>'.$activeusers2 .'</b><br /><br /></li></ol><ol class="commalist">'. $activeusers;
i.e. I just added the <li> elements around it and said to close the current ordered list and open a new one ready for the user listing.
When I release my own mod I'll include a note to say it is compatible with this one. It does depend on the execution orders (mine has to be executed first) but I'll just set mine to be an execution order of something like 1 that way it should be compatible with this/any other legend plugins that get released.