Google has changed the way you can localise searches. While the default option has usually forced you to the local search site - enter google.com and you get redirected to google.com.au - it has been possible to push Google to other locations. (If you wanted a localised British search you could go to google.co.uk, for example.) But now, the company will automatically direct you to your local Google regardless of the address you enter.
According to a blog post, the choice of country service will no longer be indicated by domain - you’ll be served the country service that corresponds to your location. As you travel, the search results will switch automatically to the country you're in.
Allegedly, this is because most people prefer localised searches but I get the feeling ensuring localised ads are served up is a signiticant driver. It's definitely an annoyance for overseas travellers who want to quickly search news and current events back home.
You can force search results to be directed to whatever country you like by changing some options. Go to the settings menu at the bottom of google.com and change the “search settings,” to choose a new location.