Ofent I found a question in a forums that "How to patch SQL Cluster" or "Patching SQL Server Cluster"
To answer this, there is nothing so special requirement but offcourse there is one thing one should consider and that is "Always patch active/primary node first". One should run SP setup on the primary node and it will get applied on the both node, we do not need to start/stop any services this is managed by SQL Server itself.
Refer section 3.2.5 Installing SQL Server 2005 SP2 on a Failover Cluster Instance
