Zen Cart does have an extensive event system. One thing I feel make it not very useful is that most events are specific to a particular page. For example there is a different NOTIFY_HEADER_START_XXX event for each different page.

In ZenMagick there is the generic controller_process_start event with the actual controller instance as event parameter. In particular plugins that need to run on each page this needs some additional work. (Not much, but there are worse examples).
So, one other outcome of my work to make plugins work (better) with Zen Cart templates is to convert Zen Cart events into ZenMagick events to tigger the same event callbacks from within a Zen Cart template.

Seeing the events using the page_stats plugin is acutally quite impressive. For example a product details page (demo DVD product) looks something like this in Zen Cart:

Compare that with the same page using a ZenMagick theme:

Again, both pages where rendered without any sideboxes.

You can spot the artificial ZenMagick events in the Zen Cart event list as the keys are lower case. The differences are even more impressive with products that have lots of attributes.