In the Exchange 2013 preview, the CAS array could still be created using "new-clientaccessarray". In the RTM version of Exchange 2013, the CMDlet is no longer available. The reason is simple: A CAS array is no longer required.
Previous Exchange Server versions used the MAPI protocol, which uses RPCoverTCP, to communicate with Outlook in the network. Unfortunately, this protocol has the serious disadvantage that it uses dynamic ports. The TCP port was therefore constantly changing, which made it difficult to configure firewalls accordingly.
Exchange 2013 now uses RPCoverHTTPS. The RPC connections are therefore completely tunneled via the HTTPS protocol. Previously, this technology was only used with Outlook Anywhere. With Exchange 2013, clients must now also use RPCoverHTTPS in the internal network.
The major advantage of RPCoverHTTPS is that it only uses port 443, i.e. no dynamic ports are used. Furthermore, an RPC endpoint is no longer required (CAS array), as the mailbox is addressed via the GUID and the UPN.
In practice, this works as follows:
Outlook receives its information via Autodiscover. Outlook sends MAILBOXGUID@UPN to a CAS server that was notified via Autodiscover. The CAS server now searches the Active Directory for the MAILBOXGUID@UPN and receives the corresponding mailbox server from the AD. The CAS server forwards the request from the Outlook client to the mailbox server hosting the mailbox.
The CAS array as an endpoint is therefore superfluous. Another advantage: cheaper load balancers can be used for the client access servers 
