No idea on stock level but you know it's only the Sprucefield PC World and Currys that are stocking them. If you find out let us know.
Other shops stocking are Argos outside Victoria Square and HMV in Donegal Arcade - there may be others... that's all I know. Could be tempted to call in with them both first before checking out the Apple queue this afternoon.
Just to save you time I wouldn't try the argos - from the looks of this site (Click "selected stores"):
http://www.argos.co.uk/static/ArgosPromo3/includeName/Apple_shop_iPad.htm
the only Argos selling iPads (though this is for the iPad 1) is Belfast Rosses Court.
I'm about 4 from the end at Goldsmiths- not as many people as I was expecting. Roll on 3pm to find out about stock and get the tickets.