The full list is available during submission of an app through iTunes Connect. (EDIT: I'd forgotten that apps are now submitted through the App Loader/Xcode, but you get the form if you edit an existing app.) The Developer Guide there shows a screenshot of the country list, though I don't know if the image is up-to-date. I'm sure the answer you pointed to simply copied-and-pasted the list from the form in iTunes Connect, as I did for this list.
Here's the full list at this time (updated with new countries as of December 2011), from the form:
Algeria
Angola
Anguilla
Antigua and Barbuda
Argentina
Armenia
Australia
Austria
Azerbaijan
Bahamas
Bahrain
Barbados
Belarus
Belgium
Belize
Bermuda
Bolivia
Botswana
Brazil
Brunei Darussalam
Bulgaria
Canada
Cayman Islands
Chile
China
Colombia
Costa Rica
Croatia
Cyprus
Czech Republic
Denmark
Dominica
Dominican Republic
Ecuador
Egypt
El Salvador
Estonia
Finland
France
Germany
Ghana
Greece
Grenada
Guatemala
Guyana
Honduras
Hong Kong
Hungary
Iceland
India
Indonesia
Ireland
Israel
Italy
Jamaica
Japan
Jordan
Kazakstan
Kenya
Korea, Republic Of
Kuwait
Latvia
Lebanon
Lithuania
Luxembourg
Macau
Macedonia, The Former Yugoslav Republic Of
Madagascar
Malaysia
Mali
Malta
Mauritius
Mexico
Moldova, Republic Of
Montserrat
Netherlands
New Zealand
Nicaragua
Niger
Nigeria
Norway
Oman
Pakistan
Panama
Paraguay
Peru
Philippines
Poland
Portugal
Qatar
Romania
Russia
Saint Kitts and Nevis
Saint Lucia
Saint Vincent and The Grenadines
Saudi Arabia
Senegal
Singapore
Slovakia
Slovenia
South Africa
Spain
Sri Lanka
Suriname
Sweden
Switzerland
Taiwan
Tanzania, United Republic Of
Thailand
Trinidad and Tobago
Tunisia
Turkey
Turks and Caicos Islands
Uganda
United Arab Emirates
United Kingdom
United States
Uruguay
Uzbekistan
Venezuela
Vietnam
Virgin Islands, British
Yemen
