Rockstar has confirmed that there'll be pre-order DLC for Grand Theft Auto V, although at the same time they warned gamers that DLC from one region wouldn't work with a copy of the game bought in another.
The region-lock warning was posted on a Rockstar support page:
It is generally recommended that you buy and play games that are designated for your country to avoid potential problems with DLC region-compatibility, such as with pre-order bonuses. For example, a North American PS3 GTAV disc (BLUS31156 code on spine of box), Japanese PS3 GTAV disc (BLJM61019 code on the spine of the box) or Asian PS3 disc (BLAS 50639 code on spine of box for Singapore, Hong Kong, Taiwan. BLKS20442 for Korea) will play on a European PlayStation3 console.
However, if you live in Europe (where the GTAV disc code is BLES01807) you will likely have a European PSN account that will not be able to redeem a US pre-order code, and will only be able to download Region 2 (European) DLC, incompatible with non-European discs.
Grand Theft Auto V is set to launch on Xbox 360 and PS3 on September 17, although there's still no word on when the game will make it over to next-gen consoles or PC.