There is a lot of advice online that if you are on an Australian IP address and set your country (in the GOG settings) to something else at the time that you purchase The Witcher 2, you will get the uncensored version. However, a lot of the discussion is from 2011. I found this post from 2012:
http://www.gog.com/news/the_witcher_2_update_of_our_geo_ip_policy
which states that it is now based on Geo IP. Has anybody tried this?

If I "hypothetically" had an Australian IP address, had my country setting to say United States, and bought TW2 in 2013, would I get the censored or uncensored version?

(I ask because I've already bought the Australian version, and I'm considering paying $5 during the sale to buy the "real" version, but I don't want to waste $5 if I'll just end up getting the AU edition again.)

Censored. Changing your location stopped working a long time ago, sadly. Two small files are the only difference between the censored version and uncensored version, though:

succubuss.dzip
elf_flotsam.dzip

Clicking should start the download, and putting the two files in your CookedPC folder will make the game 100% uncensored, making it exactly the same as the "real" uncensored version.

Thanks for the info.