I just spotted on FileConnect that Enterprise Vault 10.0.3 is released.. so go and grab it.
Whilst you're waiting for it to download, you might want to watch some of these videos over on the Connect Forums:
Exchange 2013 OWA Support (Introduction)
Exchange 2013 OWA Support (User Actions)
Exchange 2013 OWA Support (Deployment)
Exchange 2013 OWA Troubleshooting
