A new whitepaper has been published on OTN which primarily discusses best practices for AIX 5.2,5.3 and 6.1 for RAC database for avoiding node eviction due to Oprocd. It also mentions recommended AIX VMO parameters and recommended patches for Oracle RAC.
You can find the article at below location
http://www.oracle.com/technology/products/database/clusterware/pdf/rac_aix_system_stability.pdf