Bungie has given out Destiny codes to the community to unlock certain things in the game, it is unknown what these codes unlock at the moment as it tells you to check back in 2014 to see what you have unlocked.
Here are the codes and they have each been given name that relates to the game, so this could be a hint what the codes give us, possibly some kind of exclusive access to weapons, armor etc. It is unknown that if the unlocked contents can be used in the beta but more news will probably surface regarding that.
Titan - MVD-4N3-NKH
Hunter - 3DA-P4X-F6A
Warlock - YKA-RJG-MH9
Rixis achron slayer - TCN-HCD-TGY
Hive - 473-MXR-3X9
Gjallarhorn - HC3-H44-DKC
Moon - JMR-LFN-4A3
Old Russia - HDX-ALM-V4K
These codes and be redeemed at this sitehttp://www.bungie.net/en/User/redeemedcodes and they can be used by everyone so it is not first come first serve.