using subdomain on your own website

Hi.

I have seen websites that uses subdomains for each pages or "sections" of their website and was wondering if there is any advantage in doing so.

One example is this website: xxxhttp://www.homeone.com.au

If you click on the "About Us" link, the URL is xxxhttp://about.homeone.com.au, likewise the URL for the advertise link is xxxhttp://advertising.homeone.com.au

1. Is there any advantage in doing this? Would search engines rank look favourably on it, especially Google?
2. What if you have a website that deals with different topic say
- Home (home page)
- Tourism (deals with tourism in a particular areas)
- Business (deals with business opportunity in a particular areas)
- Community (deals with community services in a particular areas)

Then would having tourism.website.com, business.website.com, community.website.com be good?

Also would I be able to submit each section to a search engine and get it considered as different URL or not?

Thanks for any help.