Finally, the Exchange Team has realised that there are deployments out there which hosts more than 50 databases per server in the 2010 world!
It will be a welcome news for all Exchange architects – Exchange 2013 CU2 will put the maximum number of databases per server back to 100 for Enterprise editions, the way it was in 2010. Yes, we understand that the architectural changes forced the team to bring the count down to 50 and that the mailbox role does a lot more job than its counterpart.
But there are lot of organizations that have more than 50 databases per server in the 2010 world and the move to 2013 will be very expensive as more servers will be required. The “fix” is to wait till summer when Cumulative Update 2 for Exchange 2013 will be out.
Standard edition will only allow 5 databases per server, which is the way it has been.
Read more @ the source