TeamFortress.de somehow got their hands on the 36 new achievements for the Medic:

TF2 Medic Achivements

From looking at them, it appears that a player going through them all will be an excellent medic – answers calls from his teammates, spreads ubercharge between a few people, saving teammates from near-deaths by fire or falling, and generally kicking ass :)

I believe that this is directly linked to the statistics that show Medic the least played class.