Microsoft has released Microsoft Online Services Migration Tools

Use the Microsoft Online Services Migration Tools to forward copies of your Exchange Server mail to your Exchange Online mailboxes. You can also use the Migration Tools to copy content from your Exchange Server, POP3, or IMAP4 e-mail server mailboxes to your Exchange Online mailboxes. This product intended for use with Microsoft Online Services only.

Microsoft Online Services Migration Tools (32 bit)
Microsoft Online Services Migration Tools (64 bit)