The same features as in the 20th century plus one new: technology.
Jeff Utecht from the blog Thinking Stick may have a point. I am a teaching attending at Cleveland Clinic and residents generally respond very positively when we incorporate Web 2.0 tools during the teachings sessions -- see an example here. Actually, I prefer the term "learning session" rather than "teaching session" since this is a two-way process. Both the teacher and the students often learn from each other.
Bob Centor, SGIM President-Elect, has covered similar topics in detail on his blog DB’s Medical Rants.
What makes a well rounded teacher? Jeff Utecht
Topics Discussed During the Internal Medicine Rotation at Cleveland Clinic in October/November 2007. Clinical Cases and Images - Blog.
Using a Blog to Build an Educational Portfolio. Clinical Cases and Images - Blog.
In my day… Scoble, 01/2008.
Beautiful example of how blogs can disseminate medical information much more efficiently than journals, NEJM included (http://goo.gl/rOvNq).
Image source: Thinking Stick