CRM 2011 as of now doesn't provide ability to configure and create rollup views like Activities as of now, for example if you want to bring all the Activities of Child Accounts in single view its not possible, or you want to get all the Contacts associated to every Child Account of one parent account its not possible out of the box. its there in Activities but its limited to Related to Regarding records.
 
For organization like Banks where they deal with hierarchical structures it makes sense for them to get snapshot of all the related child objects at least Activities and Contacts to be available via one single view.