SQL Server parallelism for DML operations
SQL Server supports parallelism for some of its physical operators.

DML statements, at a high level, are logical operations. In other words, you specify what you want done, not how it's done. As long as the logical operation is maintained, SQL Server is free to satisfy the statement using any set of physical operators it deems appropriate -- that applies both to DML and DDL.

SQL Server uses the cost threshold server setting to consider using parallelism for the physical operators chosen in the query plan. There's no difference as far as parallelism is concerned between DDL and DML, because as I said, SQL Server parallelizes the physical operations (i.e., an index rebuild can use the same Index Scan physical operator as a SELECT or UPDATE query could).

So, the short answer is yes, SQL Server can parallelize DML, but aside from the cost threshold setting, you have very little control over it. (That said, it can be restricted by using things like MAXDOP hints.)



Related, but a bit aside: for a query plan that includes parallel operators, the DOP at which the query runs is selected dynamically at execution time, not at plan compile time.