Yahoo! Open Shortcuts is a new feature launched to search in yahoo. Yahoo! Shortcuts start with the exlamation mark !, which is also part of the Yahoo! logo. For example you can add a shortcut to phpmagazine.net like this :

!set ajaxmag http://www.phpmagazine.net/cgi-bin/mt/mt-search.cgi?IncludeBlogs=1&search=%s

Then search using

!ajaxmag keyword

You can find default Shortcuts such Amazon, Audio, eBay, flickr, image, mail, wiki ...You can list your own shortcuts using !list or delete using !unset shortcut. To get the help page simply type !help. Pretty easy and useful specially if you like to use your keyboard everywhere.