The SMT-LIB benchmark library is in the process of being converted from Version 1.2
to Version 2.0 of the SMT-LIB format.
This process is expected to be completed in early May 2010.
An initial Version 2.0 benchmarks is however already accessible at this location.
More benchmark will be added as they become available.
Version 1.2 benchmarsk are still available here, although their use is now deprecated.