There's a thread about it on the latest incarnation of the GH forum
http://www.grangehillfans.co.uk/schoolyard/index.php(it's on the general board...I can't link right to it for some reason!)
There's also info at
http://www.grangehillreunion.orgAlthough it's open to ex-cast members and fans of GH, I suspect it will mainly be a chance for the cast members to reunite.
As you would expect, it's being held in London, and for some reason it's on a Thursday night, which seems a strange night to pick.
I'm sure a lot of fans who would like to go to this but don't live near London will find it impossible to travel the distance midweek for a night out... Speaking for myself, if it was a weekend, it might be more feasible to make a trip to London, but as it is, I have work and family commitments so I won't be going...