Here they are yesterday in the Dominican Republic.
More at Blackfive on this entirely privately funded project. You can follow their progress and donate at Jake's blog here.
During terrible tragedies like the one unfolding now in Haiti, we all wish we could be able to offer direct and concrete assistance. These guys have the training to do so, they got there, and they can keep themselves and their patients safe. They can do more with your help.
I've just donated. It's not tax-deductable (they put this together fast), but I know that every single dollar will go to good use.