The Red Sox (.688) and Yankees (.645) each have winning percentages of .640 or higher entering August. This is the first time in the Divisional Era (since 1969) that 2 teams in the same division have had .640 or higher winning percentages entering August (via @EliasSports)
I guess this is what makes the wildcard teams worthwhile. Doesn't punish you for being in the same division as a team that is just slightly better than you overall but you are miles ahead of the winners of the other division(s).