Mario lovers in Australia will have to wait a little longer for Ninteno's new release, Mario Party 8 as it has been delayed by two weeks. Mario Party 8 is Nintendo Wii's 8th game in the series (eleventh in Japan) and is the first to be released on Nintendo's Wii console. In Australia it was scheduled for a release on July 5. However, it has been delayed by 2 weeks and will be available online and offline from July 17.

Australian Nintendo sites are assuring that it will be available from July 5 but retailers are being told of delay.
As a matter of fact Nintendo rarely sets a date for release of its games unless it's concrete so perhaps some last minute changes or translation issues have arisen.
In the new game the Star Carnival rolls into town, and Ballyhoo (who is the main host and probably the owner of the Star Carnival) along with Big Top, Ballyhoo's talking top hat, challenges everyone to the "Star Battle". The winner is crowned Superstar and triumpha a year's worth of candy with a relic called the Star Rod. Bowser also comes to rob the Star Rod, and it is depends upon the player's character how he saves the Star Carnival.
Source: Vooks