Absolutely, although where this setting is done is neither obvious nor entirely well-publicized anywhere on the Internet. You can find more information about this nifty feature is in a 2009 Tech Ed presentation by Symon Perriman of Microsoft, "Multi-Site Clustering with Windows Server 2008 Enterprise."

Clusters where every node exists within the same LAN probably don't need intra-cluster traffic encryption, but those that span to multiple sites can. If you intend to stretch your cluster to another site across a Multiprotocol Label Switching (MPLS) network or other shared Internet connection, consider encrypting your cluster communication to protect it against spying eyes.

Setting up encryption requires Windows PowerShell, specifically the Get-Cluster cmdlet. Running

Get-Cluster clusterName | fl *

against your cluster will display the full list of cluster properties. The property you're interested in for this purpose is SecurityLevel.

A SecurityLevel of 0 will use clear text for communication. A SecurityLevel of 1 (the default) will sign the traffic. Setting SecurityLevel to 2 will encrypt it communication.

Use the command

Get-Cluster clusterName | ForEach-Object \\{ $_.SecurityLevel = 2 \\}

to start encrypting.
