Parallelization for queries (SELECT) is covered quite well by the SQL engine itself, but when it comes to large volume data modifications (UPDATE, INSERT, DELETE), the standard engine does parallelize towards best use of all available resources (disk, multiple cpu-cores, etc.).
Therefore you may have a look into the approach of SQL Parallel Boost
This approach can also be used to execute multiple SQL statements in parallel.UPDATE:
A free Community Edition of SQL Parallel Boost can be downloaded at CodePlex / SQL Parallel Boost
A purely SQL engine related parallelisation solution takes advantage of minimized complexity and has no 'external' components like SSIS involved, Furthermore it's the best performing solution regarding task splitting and synchronization, as it hasn't potential connection and communication overhead. The overall performance gain thru parallelisation with SQL Parallel Boost is up to 10 !
In case you don't want to rebuild your own solution, SQL Parallel Boost provides a self-contained pure T-SQL based solution, which can be easily embedded in existing applications and ETL process tasks.