The game will be shipping in five different batches -- English (UK), English/French (US), French/German, Italian/Spanish, and Polish/Russian -- but a language pack will be available for download at launch..
Splitting up the languages has prompted Square Enix to require a bit of region locking on all retail copies of the game. If it is purchased in the UK, it must be activated on Steam in the UK. You can play it on your foreign PC so long as it's activated on a UK PC.
While it's good to know that the game itself is not region locked, the activation restriction will likely be enough frustration for those who were looking to save some money. It seems like Square Enix is really trying to support importing or, at the very least, it's not their intention to try and prevent it.
Deus Ex: Human Revolution is Region Locked [Rock, Paper, Shotgun -- Thanks De5gravity]
can cause it. You can fix it by adding *.disqus.com to your whitelists.