A bit more information is also available here:
http://beta-us.battle.net/sc2/en/forum/topic/13531371?page=1#6
Q u o t e:
Will there be unique codes for shipped games vs digital games?
Yes, both game client types (digital and physical) possess unique game activation methods.
If a player purchases the digital game client, the player will not receive a copy of the game activation key. Instead, the StarCraft II: Wings of Liberty game license will be added to the purchasing Battle.net account automatically. This is how World of Warcraft digital game clients function, as well.
If a player purchases the physical game client, the player will need to manually add the game activation key included in the boxed set to his or her Battle.net account. By adding the game activation key, the StarCraft II: Wings of Liberty game license will be added to the Battle.net account.
Q u o t e:
What exactly is region specific for activation?
Game clients that are downloaded online or installed from the physical box set will only connect to the region for which they're made. Therefore, in order for a player to log in and begin playing, both the StarCraft II: Wings of Liberty game license and the installed game client must be from the same region. If the game license and the game client don't match, the player will be unable to login.
For this reason, we do not recommend using the early digital download option if you're also purchasing the physical game client, as the risk of ending up with a game client that doesn't match your game license is much higher. Please also note that the time saved by unlocking and installing the digital download is negligible when compared to the time required to install the game using the physical DVD.
Q u o t e:
Will I be able to use my shipped SC2 activation code on the digital installer?
Once the game activation key is added to your Battle.net account and your game license is active, the option to download the client online will become available.
Please keep in mind, though, that if you try to download the game client early via the digital download option, you will want to make sure that the region of the game client you’re downloading matches the region of the game license that will be shipped to you later on. If your game license region doesn’t match the downloaded client’s region, you will not be able to login.
To clarify further, if a player purchased the North American version of StarCraft II: Wings of Liberty from a store on July 27, he or she would need to ensure that the digital game client downloaded is also from the appropriate region (in this example, from North America). Otherwise, that player would be unable to login until the North American game client is installed.
Q u o t e:
Are there any differences between a physical copy of the game and a digital downlaod?
I saw this question elsewhere, and thought it was worth answering here.
There are no differences in what each version of the game provides. All the files are exactly the same, but you obviously don't get the box, DVD, or manual.
Q u o t e:
Is the activation code tied to its game client region, or is it just the game client that is region specific?, and if so, which is the key for matching it with your Battle.net account region?
Game activation keys, game licenses, and game clients are all region-specific. As noted above, if your game license and installed game client regions don’t match, you won’t be able to login.
If the country associated with your Battle.net account (viewable in Battle.net Account Management:
https://www.battle.net/account) is accurate, you should be directed to the correct regional download when visiting this page:
http://beta-us.battle.net/en/info/digital-purchase
If you have already purchased a physical copy of StarCraft II: Wings of Liberty, but still wish to download early, you will need to make sure that the regional download matches the region for the physical game you purchased.
