From Second Life Wiki
To give a parcel of land to a group, to give an object to a group. The object becomes the property of the group. A deeded object can also change parcel media information, on a parcel it shares a group with.
NOTE: Money given to an object which has been deeded to a group also becomes the property of the group, and is distributed among members of the group who have the Accounting role "Pay group liabilities and receive group dividends".