Yup. It's essentially a delayed-start dimmer module. The same thing
is used on industrial fans which need to be speed controlled. They
might be full of kitchen grease or whatever, so the speed control
gives full power for a few seconds to get 'em going, then reduces the
mains waveform to give the lower-than-maximum running speed. The
savaplug just has a preset amount of 'dimming' compromised between
working on *most* appliances, and saving electricity.