The answer to this one, is that yes, the Canon A510 and A520 will be on the market in Australia in March 2005. Every product you read about on CNET.com.au is in fact locally available and includes Australian pricing (unless noted otherwise, as is the case sometimes with downloadable software).
The reality is that some vendor's marketing and PR departments announce products to the media before bringing their Web site and customers service teams up to speed. This procedure is a hangover from the days when announcements in print publications took weeks, if not months, to get published.
We in the online world have much faster turnarounds, so most of the time, you'll hear about it on CNET.com.au first!