Jota has started a series of Biztalk screencasts(in Portuguese), i've had the pleasure to review and comment the beta of the first episode and i might just add they are a great resource
I won't provide any spoiler, since i already know what comes ahead, but great things are coming. :-)
Read the announcement here. Or go directly to the pages that holds all the videos here.
Jota has already released two videos:
Biztalk Architecture and basic concepts and Schemas, pub/sub and message types