In early February, Facebook announced that it had 400 million users, and while nothing's certain at this point, it looks like an announcement regarding the next big milestone may be just around the corner. A new report has indicated that Facebook expects to lay claim to 500 million users in June. Nick O'Neill wrote earlier today, "Facebook is working on plans for their 500 million user celebration, projected to take place at some point before the end of June." He also wrote,