There is not much information out on the internet about extending transnational emails. I need to be able to conditionally send emails to different departments based on the category and/or SKU of the item - where is a good start?
You'll want to look at
Mage_Sales module, more specifically:
- sendNewOrderEmail (queueNewOrderEmail in CE 1.9.1)
- sendOrderUpdateEmail (queueOrderUpdateEmail in CE 1.9.1)