there won't be one this year (nice to see you there on previous demos BTW and welcome to TMA)
In case you haven't heard the hill is now all sorted with a shiny new fence (with built in rabbit traps)
and gates with combination locks for easy Druid access to pounce about ontop whenever the press are around.
Sheep will soon be roaming the hill to keep the grass down and fill in any voids that break through to the surface (AKA the new Avebury Liesure Centre)
EH had a Peer group meeting about it late last year which was so productive even the Hertigae Action chairman didn't feel the need to raise a question.
Silbury will be fixed by eminant archaeologists whenever they can be bothered to get the funding and make a name for themsleves. (nothing penciled in before 2006)