I just finished updating my Debian(unstable) box and got a shiny new version of Openoffice.org 2.0. While selecting packages when updating I also noticed that various language packs were available for it, especially Hindi and Punjabi. It is getting so common these days that one gets a choice of interface in their local language. In Linux changing to your local language is as easy as logging-out and then logging-in again in your preferred locale.
Software that I use and have several localizations include but are not limited to Seamonkey(earlier Mozilla Suite), Firefox, Thunderbird, Opera (Opera Hindi & Punjabi release), etc. Opera released its browser's version in Hindi and Punjabi for about 800 million people speaking these languages.
Not only do open source softwares offer your local language but desktop suites like GNOME (l10n status 2.12) and KDE (l10n status stable version) also offer full desktop interface in several languages. Thus increasing the reach of OSS to the furthest corners of the world.
Just last week someone asked me if it was possible to have Japanese version of Windows XP on his laptop. He had only two options: buy Japanese version of Windows XP (costs around $700) or ask a friend in Japan to buy a laptop for him and courier it here! I informed him that Linux was available in most languages for FREE :) in case he wanted to use that instead of Windoze.