Enterprise features in Windows Phone 8.1:
S/MIME to sign and encrypt email.
Access to corporate resources behind the firewall with app aware, auto-triggered VPN.
Enterprise Wi-Fi support with EAP-TLS.
Enhanced MDM policies to lock down functionality on the phone for more enterprise control, in addition to richer application management such as allowing or denying installation of certain apps.
Certificate management to enroll, update, and revoke certificates for user authentication.