I don't think that their reunion is going to be as great as they're speculating. Most people that listened to them have moved on to different genres of music, and while they may be reminiscent, I don't think people will be jumping to get tickets or albums.
I would go and see them...but not if it's too expensive. I also doubt I'd buy any sort of reunion CD - not when I already have the original ones ^^
I also think that it'd be incredibly strange to see Victoria Beckham (as she is now) reuniting with the Spice Girls, as she has changed so much since the mid 90's.