Heading into this weekend, The Dark Knight is the 9th highest money making film worldwide of all time.  Once its international tickets keep growing it will pass Return of the King to be the second highest grossing film ever.  If it doesn't pass King it will at least be the second highest domestic film. 

But Titanic still is the real King...until the final Harry Potter film opens in 2010.  Now that that final book will be split into two films, there is a change it wont pass Titanic but the foreign and domestic value of the final Potter film makes it a decent bet it will come close to the all time record.