Hi Ashutosh ,
CMS load balancing ( Clustered CMS) will load balance the request coming to BI platform between 2 or more CMS. This is taken care internally by CMS. It is suggested to have CMS machine on separate hosts. As Prateek said , hardware level load balancing will allow you to split network load across multiple servers , this can be implemented in the Webtier . .i.e. multiple appserver to handle the http request to from the user access the BI platform ( via BI launchpad , CMC...) via the hardware load balancer like BIG -ip.
Also you can have multiple webi servers to load balance the users for webi reports.
Regards ,
Abhinav