Metallica for Reading 08?

Metal Hammer reported that there are rumours that Metallica and Rage Against the Machine may be playing The Reading and Leeds Festival this year:

Here are some rumours we've heard with regards to who might be playing the Reading/Leeds festivals this year.

Reading Festival - Friday 22nd to Sunday 24th August 2008
Main Stage >> Friday 22 August >> Rage Against The Machine - strong rumour
Metallica - strong rumour >> unknown day
My Chemical Romance - rumour >> unknown stage >> unknown day
NoFX - strong rumour