Is there a way to subscribe everyone who is a member of a specific Team Area to a work item

not out of the box.. you could write a java server extension to do this..

I sencond Sam's answer. I posted several articles here: http://rsjazz.wordpress.com that talk about the bits. There are several example participants, they show how to modify a work item and there is API described that shows how to subscribe to a work item. The last post shows how to get and iterate team/project/process areas. The Extension workshop referred to in several posts will provide you with the dev client setup.