Were you and any of your friends planning on buying Warhawk, and simply downloading it onto each other's consoles? Unfortunately that wont be possible. You can by all means download it on upto five consoles, however only the account that was used to buy the game will be able to play on it... so if you have a sibling with another account, I'm afraid they will have to use your account to play WarHawk as well. Found on the screen before you download the game is a little snippet

"One time fee for download or use solely by the purchasing PSN account on up to five PS3 units, with no more than one activated PS3 unit within a 24 hour period. Content may not be used by any other account."

This isn't simply a development in how games will work from now on however, when asked by Gamespot, a representative answered their questions, clearly stating that, whilst this was what they did this time round, when future games are released on the PSN, they will evaluate each game as they are released based on the costs of development, maintenance, server and other.

Fortunately, those that may want to play WarHawk with their friends, can simply buy the BD version of the game, which will not have the same restrictions placed on it, as the downloadable version.

We must take steps to protect the investment we have made in our products. The development costs of Warhawk are no different than any other boxed game you might find from SCEA at retail. Couple that with the cost to maintain a continuous online gameplay environment and you can understand the investment we have made in Warhawk. Not utilizing this new DRM strategy could open the company up to losses that could jeopardize our ability to allow free online gameplay across the PlayStation Network.