SystemVerilog includes functions for controlling and reporting the randomization settings (see section 17.13 of the draft 3 p1800 standard that is available from the IEEE).
srandom allows you to specify the seed that is used by an object or process.
get_randstate returns a string containing the current state of the random number generator
set_randstate allows you to set (restore) the random number generator state using a string (from an earlier call to get_randstate).
The ovm_object class has a reseed function that generates a random seed from an object's type name and hierarchical path which it then passes to srandom. This mechanism can be disabled by setting the static member ovm_object::use_ovm_seeding = 0 (the default is 1).
The reseed function is called for ovm_sequence_item to ensure sequences get random seeds. You can also call it for any other object derived from ovm_object, e.g. a custom stimulus generator.
Hope that answers your question.