SDL SmartTarget 2011 SP3 Content Delivery Logback configuration example. From SmartTarget installation media.
<?xml version="1.0" encoding="UTF-8"?>
<configuration scan="true">
<!-- Properties -->
<property name="log.pattern" value="%date %-5level %logger{0} - %message%n"/>
<property name="log.history" value="7"/>
<property name="log.folder" value="c:/tridion/log"/>
<property name="log.level" value="WARN"/>
<!-- Appenders -->
<appender name="rollingSmartTargetLog" class="ch.qos.logback.core.rolling.RollingFileAppender">
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<fileNamePattern>${log.folder}/smarttarget.%d{yyyy-MM-dd}.log</fileNamePattern>
<maxHistory>${log.history}</maxHistory>
</rollingPolicy>
<encoder>
<pattern>${log.pattern}</pattern>
</encoder>
<prudent>true</prudent>
</appender>
<!-- Loggers -->
<!-- All Java based smarttarget -->
<logger name="com.tridion.smarttarget" level="${log.level}">
<appender-ref ref="rollingSmartTargetLog"/>
</logger>
<!-- specific one for ambientdata -->
<logger name="com.tridion.smarttarget.ambientdata" level="${log.level}">
<appender-ref ref="rollingSmartTargetLog"/>
</logger>
<!-- all .Net logs through Juggernet -->
<logger name="Tridion.SmartTarget" level="${log.level}">
<appender-ref ref="rollingSmartTargetLog"/>
</logger>
</configuration>