We are going to encrypt the Oracle11gR2 database on which SAP application is running.
Please let us know if any additional steps needs to be taken? like any considerations or specific testing is needed.
We are going to use TDE tablespace encryption
You should check this (tablespace encryption is officially supported on SAP 6.40_EX2+ (UNIX and Linux only)).
Also check this document: http://www.oracle.com/us/solutions/sap/wp-ora4sap-tde11g-303816.pdf (it's a bit old but gives you enough information).
Other than that you should be ok, because Tablespace TDE is enfored on I/O level, so it doesn't affect application.