Are you talking about the email widget on your homescreen? All your mail accounts are now together in that one widget. If you tap it, you'll go to the last account you were looking at. If you want to change accounts, tap the bars on the upper left side of your screen, and all your email accounts will show up. I have an AOL account and 2 gmail accounts, and they are all listed. The numeral on your email widget is the total number of emails from all your accounts. I rather like that they're all together so I can check them all pretty quickly, basically from one screen rather than having to open each account separately.
Also, when you get an email, it'll show up in the status bar (provided you have notifications enabled). If you receive an email in more than one account, you'll have a notification for each account in the status bar; that way you know you need to check several accounts, if that's the case.
Hope this helps.