This may not be the best place to ask this, but I'll try here first.

When an order is placed and it is successful, the order is taken from Pending to Processing automagically whether or not I'm logged in to see it (if a tree falls in the for forest...)

How can I get I add to the functionality at that stage?

Basically I want to trigger some other code at that point in time. So when a successful order comes in, do "this". How do I hook into that event, so to speak?

Clues?