From these valued sources it appears that it should be dry, or barely noticeable rain, and pretty warm too. Also its supposed to be well hot this weekend!
I think with all the 'chance' of rain talk we're gonna have to expect a few showers although I can't see it being a mud bath as it takes quite a raining to get it all muddy, especially as it'll be so hot in the previous few days.
Could I also point out that I correctly predicted 14 days ago that today would be warm and sunny? (http://www.hannahmorezider.co.uk/Glastonbury/05Weather.htm) If we get a bit of light rain this afternoon remember where you heard it first!
Taking a waterproof jacket cos its Glasto so its bound to rain sometime, wellies will be staying the car, where I can get them if things start turning nasty.