By comparison, the Xbox 360 community is about halfway there (37 million team actions), and the PS3 community trails that total by 10 million. What's a team action? It's the three Rs and an H. And an S. Resupply, revive, repair, heal and spot. Any of those carried out in BFBC2 Vietnam, retroactive to its release date, counts toward the unlock total.
The glorious PC community's triumph could be attributed to any number of factors. Maybe it has more players, or more players putting in more time. Or maybe they are more selfless and public-spirited.