I can confirm it IS supported for 11G, you can check your specific platform here:
http://support.nimsoft.com/downloads/doc/Platform_Support_Availability_current.pdf
Also check this from the product release notes (old but still vaild):
1. Make sure, the Oracle Client is set up and configured correctly. Oracle libraries have to be in system PATH. On LINUX the environmental variables ORACLE_SID and ORACLE_HOME have to be set for the Nimsoft controller. This can be done either in the controller GUI, or by editing the starting script 'nimbus', usualy located at /etc/init.d (the robot needs to be restarted).
2. Get the package oracle.zip from Internet Updates.
3. Get a valid license from http://www.nimsoft.no
. 4. Install oracle.zip on the machine running Oracle Client (use drag & drop from Nimbus Archive).
5. Double click on oracle probe to launch probe property sheet.
6. Configure the probe acc. to your specifications and connection requirements.
Note: On UNIX/Linux platforms make sure the $ORACLE_HOME libraries are in the pathbefore starting Nimsoft robot.
To load the shared libraries on Linux machine make sure “Current Enforcing Mode” of SELinux is set to permissive mode.
Supported Oracle versions and clients For supported combinations of Oracle servers and clients, please see the probe documentation.