$.fn.blink = function(opts) {
   // allows $elem.blink('stop');
   if (opts == 'stop') {
     // sets 'blinkStop' on element to true, stops animations, 
     // and shows the element.  Return this for chaining.
     return this.data('blinkStop', true).stop(true, true).show();
   }

   // we aren't stopping, so lets set the blinkStop to false,
   this.data('blinkStop', false);

   // load up some default options, and allow overriding them:
   opts = $.extend({}, {
     fadeIn: 100,
     fadeOut: 300
   }, opts || {} );

   function doFadeOut($elem) {
     $elem = $elem || $(this); // so it can be called as a callback too
     if ($elem.data('blinkStop')) return;
     $elem.fadeOut(opts.fadeOut, doFadeIn);
   }
   function doFadeIn($elem) {
     $elem = $elem || $(this);
     if ($elem.data('blinkStop')) return;
     $elem.fadeIn(opts.fadeIn, doFadeOut);
   }
   doFadeOut(this);
   return this;
 };
/*
// example usage - blink all links until you mouseover:
 // takes advantage of the jQuery.one() function so that it only calls the 
 // stop blink once
 $('a').blink({fadeIn: 500, fadeOut: 1500}).one('mouseover', function() { 
   $(this).blink('stop') 
 });

 // 30 seconds after we started blinking, stop blinking every element we started:
 setTimeout(function() { 
   $('a').blink('stop');
 }, 30000);

 // example that should do what you wanted:
 $("#mydiv1,#mydiv2").blink().one('mouseover', function() {
   $(this).blink('stop');
 });

*/