As a side note: one thing to keep in mind regarding listener/software versions...

If you're using grid control (with intelligent agent) to monitor your systems, and you have multiple oracle_home's on some hosts, agent will report each and every listener to be located in the same installation directory (latest version it has found) regardless from which oracle_home it actually is running. In other words, the oracle_home in grid control for multiple listeners on one host is *always wrong* for all listeners except the one listener that runs the latest vesion of the software.

Stefan