I really really hope there isnt an experience cap on this game. It was incredibly annoying in baldur's gate not to be able to fully develop your characters.

As far as I've heard, it'll be pretty much like BG II, somewhere close to 3 million. Others say you'll be able to reach something close to level 20, depending on your character.
What everyone seems to say is: Let's wait and see.

In fact the XP-cap is 1.801.000. So your characters will be allowed to reach level 14-17, depending on your class off course.

More wise-crack:
BioWare says that druids have to stay at level 14 because their abilities, should the reach a further level, would be too difficult to implement in the game but they don't rule it out for a possible expansion pack.