On the Wave team here in Sydney, we have a number of both local Australians and imported Europeans who are incredibly passionate about sports, so we wanted to do something to let people like us use Wave to get excited about the World Cup.
With the help of various Wave APIs and a team of similarly sports-crazy developers in India, we created Google Wave Football Fever. From this site, people can create both prediction waves (important) and party planning waves (vital). Here's what our "Germany v Australia" prediction wave looked like - I didn't do so bad!
There are still a few more Australia games left in the first round, so you've got time to try out Wave Football Fever for predicting their outcomes.
We also have a team member and local, Pat Coleman, who's live-waving various games for fun. You can check out his index of live waves here. You'll notice there's no live wave for Australia v Germany - that's because we were all at Darling Harbour, trying to watch the game along with thousands of other nightowl Australians :-)
Enjoy the World Cup!