* Great work on taking the time to build something cool.
* Awesome work at keeping the functionality simple, intuitive and easy to use. Most people fail at pulling that off.
* Much props for asking for feedback.
...as for the design...
* Some boxes have sharp corners, some have round. Pick just one for a uniform look. You can put stuff like the Facebook fan widget inside a section with rounded corners.
* Doesn't fit in a width of 1024px.
* That green background is hideous and is causing me much gnashing of teeth.
* The logo doesn't seem to fit the rest of the page, in style or in size.
* What is that giant empty blue bar between the header and body of the front page supposed to be doing?
* Some of the small rounded boxes with text in them ("World Cup 2011 Contest coming soon") are center-aligned, but off-center.
* Heading on the left nav bar on the match page could use more uniform spacing so that the match name (sort of redundant) doesn't look like its trying to break free from its rounded div prison to re-join its slightly larger twin to the right.
Other than that, looks great.