Today Propel 1.4 was released and it contains some debugging goodies. We can use the DebugPDO class to get the nifty logging into the Web Debug Panel. However some more interesting information is turned off by default by Propel.
Features include time logging, memory logging and slow query logging - all that are simple to enable in your configuration under the details for your propel connection. You can see an example of the output from the logging here.