jQuery's no-conflict mode: yet another reason why it's the best
It took me a bit to find out why jQuery (now bundled with WordPress) was not working as I expected inside of the WP admin area. The script was being called, but my code like $("#foo") was not working. I really had no clue where to begin, since it still has all those old JS libraries/frameworks being called as well. It was due to Prototype being packaged with it and conflicting with the "$" shortcut.
Long story short, jQuery already planned for library conflicts and has a quick solution. The no-conflict mode allows you to define your own shortcut, and of course it works like a charm.
It's easy to do - just put this line in your code somewhere:
var J = jQuery.noConflict();
Now $("#foo") will be J("#foo") and it will not conflict with any other libraries that may be installed. I hope WP gets rid of all the other stuff and goes with pure jQuery and plugins soon enough though 
great solution is it global for all jquery's functions used by different plugin like fancybox,thickbox ..on a same website? i'm looking for that
thanks
Perfect thanks for the quick explaination. Don't know why other sites have to write long articles on how to do it, not got time to read all that just want a quick fix and this is it!
Thanks for this, but i still can't get my slider working correctly without conflicts.. soon as i enable any WP plugins my slider stops working.. any ideas ?
Huge thanks in advance to anyone who can help with this
I'd say find a jQuery-based slider that works with your version. That's the best I can say.
Great this is so simple.
Thanks for sharing with us.