I liked this presentation by Erik Rozendaal on lightweight event sourcing:
http://www.slideshare.net/dlrozendaal/exploring-lightweight-event-sourcing-goto-amsterdam-2011
He made a similar presentation at Scala Days 2011; the video is not available yet, but supposedly it will show up here eventually:
http://days2011.scala-lang.org/node/138/301
It seems quite practical!