I'm coming from the Java world, and SilverStripe is the first PHP framework I worked with (and actually the first PHP code I worked with).
It is quite difficult to understand the framework, when I'm not really understand the PHP syntax and the way of programming with it. (again, that is my first php code).
To help me walk through the code, I wanted good logging system. The SilverStripe logger with quite simple (unless I miss something...), and I want something I'm familiar with. I foound the Log4php which is php version of Log4J, a very commonly used logger framework in java.
I created SilverStripe module for this Log4php framework.
It support different level of logs (DEBUG, INFO, WARN, ERROR and FATAL), and can direct its output to a file, the console, a remote server using TCP, a remote Unix Syslog daemon, to the NT EventLog, to Database or even send e-mail (and more....)
eg. it can write to file any log message and send e-mail for error messages.
More on log4php at http://incubator.apache.org/log4php/
(more on the apache logging frameworks: http://logging.apache.org/)
Please note that it released under the Apache License, because the log4php is under this license. (http://www.apache.org/licenses/LICENSE-2.0)