Wrong: The hard runway is back in action as is the grass so you have a choice.
Only problem now is that the hard runway edge is 'sharp' so you can only exit at tarmac taxiways.
This is going to cause chaos at airshow fly-ins when formerly you could just turn off the runway at any point to the southside parking.
Every a/c landing on the hard will have to taxi to the end which will I predict cause the FISOs a big headache.
And as previous poster says you must phone for PPR 01223 833376, and if you want to fly in for an airshow day you must book a landing slot as well: you must have read the AIC yellow 239
http://www.ais.org.uk/aes/pubs/aip/pdf/aic/4Y239.PDF
before you ring them as they'll want to know which entry/exit gate you want.
Sounds daunting but really it isn't and Duxford, airshow or not makes an excellent day out.
Enjoy
Cusco