His name is Eduardo Rodriguez Veltze, he has been a judge in the supreme court, and he appears, at this stage at least, as an interim, compromise candidate:
The action came after lawmakers gathered following a day of demonstrations and under a warning by the military of possible intervention if the spreading chaos isn’t quelled.
Congress rapidly accepted the resignation of President Carlos Mesa. Then both the Senate and House leaders rejected the job, automatically giving it to Supreme Court Justice Eduardo Rodriguez Veltze, who had been third in the line for the presidency.
“Bolivia deserves better days,” Rodriguez told lawmakers after swearing in. “I’m convinced that one of my tasks will be to begin an electoral process to renew and continue building a democratic system that is more just.”
Publius Pundit has another good Bolivian blogs roundup. In particular Mabb has a good on the spot account of the tension involved.
Interestingly enough Miguel at Ciao and Eduardo Barrio Flores are arguing that opposition leader Evo Morales should resign too, in order to reduce the dangers of this conflict exploding.