Ubercart: Messin' With Email Templates
If this Quicktip saves one person as much time as it should have saved me, then consider this post a success.
When setting up your Ubercart-powered site, be sure to set the input formats for the email templates correctly - otherwise the super-pretty default HTML templates that get are supposed to be sent out will instead be sent as plain, unformatted, difficult-to-read text.