The bookmarklet has been removed from WP 2.5.
According to Matt it’ll be making a return in 2.6 better than ever.
You can still use the 2.3 bookmarklet, which you can find on this page: https://codex.www.ads-software.com/Press_It
I also wrote these ones up awhile ago since the default one didnt support Opera very well:
New Window/tab: javascript:function A(b){return (encodeURIComponent)?encodeURIComponent(b):escape(b);}Q='';if(window.getSelection){Q=window.getSelection();}else if (document.getSelection){Q=document.getSelection()}else if(document.selection){Q=document.selection.createRange().text;}void(window.open('https://site-url/wp-admin/post-new.php?text='+A(Q)+'&popupurl='+A(location.href)+'&popuptitle='+A(document.title)));
One which works in the current window: javascript:function A(b){return (encodeURIComponent)?encodeURIComponent(b):escape(b);}Q='';if(window.getSelection){Q=window.getSelection();}else if (document.getSelection){Q=document.getSelection()}else if(document.selection){Q=document.selection.createRange().text;}location.href='https://site-url/wp-admin/post-new.php?text='+A(Q)+'&popupurl='+A(location.href)+'&popuptitle='+A(document.title);
You’ll need to update the ‘site-url’ in the link to be useful though.
Just create a new bookmark and set those as the URL..