andWhy is "xxx.blogspot.com" now redirecting to "xxx.blogspot.com.au"?
Why was my blog address recently changed from ".com" to ".in"?
Blogger will host our blog content using country code relevant aliases, according to the unique laws of each different country.
The local country domain URL is determined using geolocation.
The relevant CC alias will be accessed automatically, according to the network location of the reader in question. These aliases are being added on a country by country basis, with Australia ("blogspot.com.au") and India ("blogspot.in") apparently recently deployed.
This will let Blogger remove content, that's illegal in one country, without having to remove that same content for all of your readers, worldwide. You benefit, because your blog won't go offline, for the entire world, when you publish something that's illegal in one single country.
A BlogSpot blog, with a standard header, will be indexed under "blogspot.com".
With any BlogSpot published blog containing a standard Blogger header, the blog will have a canonical reference to the "blogspot.com" alias. The search engines will index the blog, using the "blogspot.com" alias - even when following a country code specific link.
The search engine ranking of your blog won't be affected - except that a blog, left online in most countries, will get more traffic than one taken offline worldwide. When you check the Page Rank, you should continue to check the "blogspot.com" URL, because all search engine reputation will accumulate under the "blogspot.com" alias.
Owners of blogs with custom templates should check the template.
Owners of older or uniquely developed blogs, possibly using Classic or highly customised templates, may want to check the headers in their blogs, and make sure that they have a "canonical" tag referencing their "blogspot.com" alias.
Blogs published to non "blogspot.com" URLs, using properly setup and fully operational "custom domain" publishing, will not be affected - as the default "blogspot.com" URL is already redirected to the domain URL. While a newly purchased custom domain is "In Transition", the domain redirect will not be in effect - and the "blogspot.com" URL will be subject to CC alias redirect.
Any reader using a browser or computer that's affected by domain based filters will need to check all filters. Add "blogspot.com.au", "blogspot.in", "blogspot.jp", or any other relevant country, wherever "blogspot.com" is specified.
Note that geolocation will produce anomalies in odd cases.
Note that the redirect uses geolocation, to identify a relevant country code. Readers in small countries, or located near the border of other countries, may be using an ISP located in a different country, and may find their personal redirect reflecting the other country.
Any reader wishing to bypass the local alias can access a "no country redirect" alias using the URL of "blogspot.com/ncr". Similar to the "ncr" URL modifier used to bypass local language redirects of "blogger.com", this will give access to the U.S. English alias of the blog of your choice.