I expect Google Calendar to become HUGE. Mainly due to the fact that it's so easy to create and maintain a public calendar (or one that you share with your friends).
Me and Mattias for instance, we have already created "gbg-nöje", which is a public calendar that we both maintain. Not to aid others, but still, useful for a selected few atleast :)
If someone would have the energy to maintain a full-blown Gothenburg club guide, that'd be awesome. Not me though, way too lazy. Carry on!
Now I just have to convince Anna that she should have one as well, and share it with me, so that I have full knowledge of what we got planned and whatnot!