gistfile1.js

(function($)
{
    $.fn.myPlugin = function(optionsOrCommand, commandOptions)
    {            
        if (optionsOrCommand == 'someCommand')
        {
            return this.each(function()
            {   
                this.myPlugin.someOtherFunction();
            });
        }

        var opts = $.extend($.fn.myPlugin.defaults, optionsOrCommand);
        return this.each(function()
        {        
            if (this.myPlugin) { return false; }
            var $this = $(this);                        
            var c =
            {
                initialize: function()
                {                       
                  c.someOtherFunction();
                },                                
                someOtherFunction: function()
                {

                }                
            }            
            this.myPlugin = c;
            c.initialize();
        });
    };
})(jQuery);

$.fn.myPlugin.defaults = 
{
    someValue: 'aDefault', 
};

/*
by default you initialize it with a straightforward call:
$('something').myPlugin({settings});

but you can also call specific actions after initialization via commands:

$('something').myPlugin('someCommand'); 

or pass options to those commands:
$('something').myPlugin('someCommand', {options}); 
*/

except the defaults should go inside the closure.

also, a little-known shortcut to (function($){ ... })(jQuery); is:

jQuery(function($){ ... }); // saves 2. whole. characters. ;)