From Murray Chandler & Helen Milligan's site:
There has been an important change to the Grand Prix rules for 2010. The requirement for a tournament to have three players in a division before Grand Prix points are awarded has been removed. This will benefit strong players who travel to the more distant events - Open Grand Prix points will now be awarded even if there are fewer than 3 players rated over 2000.
This change is overdue but also very welcome. I'm pleasantly surprised because I argued several years ago that the NZ grand prix system heavily favoured Aucklanders and that restrictions like having to have three players in a division led to distortions but it fell on deaf ears (despite clear evidence for my case). Since then the vast majority of prize-winners each year have been Aucklanders, with the unsurprising result that the annual grand prix has failed to spark much interest outside Auckland.
Here in Australia a few players (like me) might win events in Tasmania or WA and score a few admittedly 'soft' grand prix points but the Australian experience clearly shows that this has little or no bearing on the overall result in any given division.