The Steam Wallet Beta, Steamworks’ newest feature, is now live and will allow steam users to add value to their Steam account using the current available payment methods supported by Steam. These funds can be later used to make purchases from the Steam Store.
This could be a feature in preparation for Steamworks’ launch on the PS3 or a useful way for young gamers who don’t have access to intangible currency(as pointed out by joystiq).
Valve announced the feature in the Steam forums,
To help us test this new feature, now in beta, click here and follow the instructions available there. Remember, even in beta, purchases are real. You should only fund with money you actually plan to use on Steam.
via Shacknews